register_sched_domain_sysctl() copies the cpu_possible_mask into
sd_sysctl_cpus, but only if sd_sysctl_cpus hasn't already been
allocated (ie, CONFIG_CPUMASK_OFFSTACK is set). However, when
CONFIG_CPUMASK_OFFSTACK is not set, sd_sysctl_cpus is left
uninitialized (all zeroes) and the kernel may fail to initialize
sched_domain sysctl entries for all possible CPUs.
This is visible to the user if the kernel is booted with maxcpus=n, or
if ACPI tables have been modified to leave CPUs offline, and then
checking for missing /proc/sys/kernel/sched_domain/cpu* entries.
Fix this by separating the allocation and initialization, and adding a
flag to initialize the possible CPU entries while system booting only.
Tested-by: Syuuichirou Ishii <ishii.shuuichir@jp.fujitsu.com>
Tested-by: Tarumizu, Kohei <tarumizu.kohei@jp.fujitsu.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190129151245.5073-1-msys.mizuma@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".
The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:
#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
# define HAVE_JUMP_LABEL
#endif
We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.
Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
We already have task_has_rt_policy() and task_has_dl_policy() helpers,
create task_has_idle_policy() as well and update sched core to start
using it.
While at it, use task_has_dl_policy() at one more place.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/ce3915d5b490fc81af926a3b6bfb775e7188e005.1541416894.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 timer updates from Thomas Gleixner:
"Early TSC based time stamping to allow better boot time analysis.
This comes with a general cleanup of the TSC calibration code which
grew warts and duct taping over the years and removes 250 lines of
code. Initiated and mostly implemented by Pavel with help from various
folks"
* 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
x86/kvmclock: Mark kvm_get_preset_lpj() as __init
x86/tsc: Consolidate init code
sched/clock: Disable interrupts when calling generic_sched_clock_init()
timekeeping: Prevent false warning when persistent clock is not available
sched/clock: Close a hole in sched_clock_init()
x86/tsc: Make use of tsc_calibrate_cpu_early()
x86/tsc: Split native_calibrate_cpu() into early and late parts
sched/clock: Use static key for sched_clock_running
sched/clock: Enable sched clock early
sched/clock: Move sched clock initialization and merge with generic clock
x86/tsc: Use TSC as sched clock early
x86/tsc: Initialize cyc2ns when tsc frequency is determined
x86/tsc: Calibrate tsc only once
ARM/time: Remove read_boot_clock64()
s390/time: Remove read_boot_clock64()
timekeeping: Default boot time offset to local_clock()
timekeeping: Replace read_boot_clock64() with read_persistent_wall_and_boot_offset()
s390/time: Add read_persistent_wall_and_boot_offset()
x86/xen/time: Output xen sched_clock time from 0
x86/xen/time: Initialize pv xen time in init_hypervisor_platform()
...
Fix the order in which the private and shared numa faults are getting
printed.
No functional changes.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25215.7 25375.3 0.63
1 72107 72617 0.70
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-7-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
match_string() returns the index of an array for a matching string,
which can be used instead of the open coded variant.
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/1527765086-19873-15-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Variants of proc_create{,_data} that directly take a struct seq_operations
argument and drastically reduces the boilerplate code in the callers.
All trivial callers converted over.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Pull scheduler updates from Ingo Molnar:
"The main scheduler changes in this cycle were:
- NUMA balancing improvements (Mel Gorman)
- Further load tracking improvements (Patrick Bellasi)
- Various NOHZ balancing cleanups and optimizations (Peter Zijlstra)
- Improve blocked load handling, in particular we can now reduce and
eventually stop periodic load updates on 'very idle' CPUs. (Vincent
Guittot)
- On isolated CPUs offload the final 1Hz scheduler tick as well, plus
related cleanups and reorganization. (Frederic Weisbecker)
- Core scheduler code cleanups (Ingo Molnar)"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits)
sched/core: Update preempt_notifier_key to modern API
sched/cpufreq: Rate limits for SCHED_DEADLINE
sched/fair: Update util_est only on util_avg updates
sched/cpufreq/schedutil: Use util_est for OPP selection
sched/fair: Use util_est in LB and WU paths
sched/fair: Add util_est on top of PELT
sched/core: Remove TASK_ALL
sched/completions: Use bool in try_wait_for_completion()
sched/fair: Update blocked load when newly idle
sched/fair: Move idle_balance()
sched/nohz: Merge CONFIG_NO_HZ_COMMON blocks
sched/fair: Move rebalance_domains()
sched/nohz: Optimize nohz_idle_balance()
sched/fair: Reduce the periodic update duration
sched/nohz: Stop NOHZ stats when decayed
sched/cpufreq: Provide migration hint
sched/nohz: Clean up nohz enter/exit
sched/fair: Update blocked load from NEWIDLE
sched/fair: Add NOHZ stats balancing
sched/fair: Restructure nohz_balance_kick()
...
Scheduler debug stats include newlines that display out of alignment
when prefixed by timestamps. For example, the dmesg utility:
% echo t > /proc/sysrq-trigger
% dmesg
...
[ 83.124251]
runnable tasks:
S task PID tree-key switches prio wait-time
sum-exec sum-sleep
-----------------------------------------------------------------------------------------------------------
At the same time, some syslog utilities (like rsyslog by default) don't
like the additional newlines control characters, saving lines like this
to /var/log/messages:
Mar 16 16:02:29 localhost kernel: #012runnable tasks:#012 S task PID tree-key ...
^^^^ ^^^^
Clean these up by moving newline characters to their own SEQ_printf
invocation. This leaves the /proc/sched_debug unchanged, but brings the
entire output into alignment when prefixed:
% echo t > /proc/sysrq-trigger
% dmesg
...
[ 62.410368] runnable tasks:
[ 62.410368] S task PID tree-key switches prio wait-time sum-exec sum-sleep
[ 62.410369] -----------------------------------------------------------------------------------------------------------
[ 62.410369] I kworker/u12:0 5 1932.215593 332 120 0.000000 3.621252 0.000000 0 0 /
and no escaped control characters from rsyslog in /var/log/messages:
Mar 16 16:15:06 localhost kernel: runnable tasks:
Mar 16 16:15:06 localhost kernel: S task PID tree-key ...
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1521484555-8620-3-git-send-email-joe.lawrence@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the SEQ_printf() macro prints to the console, it runs a simple
printk() without KERN_CONT "continued" line printing. The result of
this is oddly wrapped task info, for example:
% echo t > /proc/sysrq-trigger
% dmesg
...
runnable tasks:
...
[ 29.608611] I
[ 29.608613] rcu_sched 8 3252.013846 4087 120
[ 29.608614] 0.000000 29.090111 0.000000
[ 29.608615] 0 0
[ 29.608616] /
Modify SEQ_printf to use pr_cont() for expected one-line results:
% echo t > /proc/sysrq-trigger
% dmesg
...
runnable tasks:
...
[ 106.716329] S cpuhp/5 37 2006.315026 14 120 0.000000 0.496893 0.000000 0 0 /
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1521484555-8620-2-git-send-email-joe.lawrence@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The util_avg signal computed by PELT is too variable for some use-cases.
For example, a big task waking up after a long sleep period will have its
utilization almost completely decayed. This introduces some latency before
schedutil will be able to pick the best frequency to run a task.
The same issue can affect task placement. Indeed, since the task
utilization is already decayed at wakeup, when the task is enqueued in a
CPU, this can result in a CPU running a big task as being temporarily
represented as being almost empty. This leads to a race condition where
other tasks can be potentially allocated on a CPU which just started to run
a big task which slept for a relatively long period.
Moreover, the PELT utilization of a task can be updated every [ms], thus
making it a continuously changing value for certain longer running
tasks. This means that the instantaneous PELT utilization of a RUNNING
task is not really meaningful to properly support scheduler decisions.
For all these reasons, a more stable signal can do a better job of
representing the expected/estimated utilization of a task/cfs_rq.
Such a signal can be easily created on top of PELT by still using it as
an estimator which produces values to be aggregated on meaningful
events.
This patch adds a simple implementation of util_est, a new signal built on
top of PELT's util_avg where:
util_est(task) = max(task::util_avg, f(task::util_avg@dequeue))
This allows to remember how big a task has been reported by PELT in its
previous activations via f(task::util_avg@dequeue), which is the new
_task_util_est(struct task_struct*) function added by this patch.
If a task should change its behavior and it runs longer in a new
activation, after a certain time its util_est will just track the
original PELT signal (i.e. task::util_avg).
The estimated utilization of cfs_rq is defined only for root ones.
That's because the only sensible consumer of this signal are the
scheduler and schedutil when looking for the overall CPU utilization
due to FAIR tasks.
For this reason, the estimated utilization of a root cfs_rq is simply
defined as:
util_est(cfs_rq) = max(cfs_rq::util_avg, cfs_rq::util_est::enqueued)
where:
cfs_rq::util_est::enqueued = sum(_task_util_est(task))
for each RUNNABLE task on that root cfs_rq
It's worth noting that the estimated utilization is tracked only for
objects of interests, specifically:
- Tasks: to better support tasks placement decisions
- root cfs_rqs: to better support both tasks placement decisions as
well as frequencies selection
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Do the following cleanups and simplifications:
- sched/sched.h already includes <asm/paravirt.h>, so no need to
include it in sched/core.c again.
- order the <linux/sched/*.h> headers alphabetically
- add all <linux/sched/*.h> headers to kernel/sched/sched.h
- remove all unnecessary includes from the .c files that
are already included in kernel/sched/sched.h.
Finally, make all scheduler .c files use a single common header:
#include "sched.h"
... which now contains a union of the relied upon headers.
This makes the various .c files easier to read and easier to handle.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The load balancer uses runnable_load_avg as load indicator. For
!cgroup this is:
runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq
That is, a direct sum of all runnable tasks on that runqueue. As
opposed to load_avg, which is a sum of all tasks on the runqueue,
which includes a blocked component.
However, in the cgroup case, this comes apart since the group entities
are always runnable, even if most of their constituent entities are
blocked.
Therefore introduce a runnable_weight which for task entities is the
same as the regular weight, but for group entities is a fraction of
the entity weight and represents the runnable part of the group
runqueue.
Then propagate this load through the PELT hierarchy to arrive at an
effective runnable load avgerage -- which we should not confuse with
the canonical runnable load average.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When an entity migrates in (or out) of a runqueue, we need to add (or
remove) its contribution from the entire PELT hierarchy, because even
non-runnable entities are included in the load average sums.
In order to do this we have some propagation logic that updates the
PELT tree, however the way it 'propagates' the runnable (or load)
change is (more or less):
tg->weight * grq->avg.load_avg
ge->avg.load_avg = ------------------------------
tg->load_avg
But that is the expression for ge->weight, and per the definition of
load_avg:
ge->avg.load_avg := ge->weight * ge->avg.runnable_avg
That destroys the runnable_avg (by setting it to 1) we wanted to
propagate.
Instead directly propagate runnable_sum.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since on wakeup migration we don't hold the rq->lock for the old CPU
we cannot update its state. Instead we add the removed 'load' to an
atomic variable and have the next update on that CPU collect and
process it.
Currently we have 2 atomic variables; which already have the issue
that they can be read out-of-sync. Also, two atomic ops on a single
cacheline is already more expensive than an uncontended lock.
Since we want to add more, convert the thing over to an explicit
cacheline with a lock in.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Ingo Molnar:
"Three CPU hotplug related fixes and a debugging improvement"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/debug: Add debugfs knob for "sched_debug"
sched/core: WARN() when migrating to an offline CPU
sched/fair: Plug hole between hotplug and active_load_balance()
sched/fair: Avoid newidle balance for !active CPUs
I'm forever late for editing my kernel cmdline, add a runtime knob to
disable the "sched_debug" thing.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170907150614.142924283@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently we unconditionally destroy all sysctl bits and regenerate
them after we've rebuild the domains (even if that rebuild is a
no-op).
And since we unconditionally (re)build the sysctl for all possible
CPUs, onlining all CPUs gets us O(n^2) time. Instead change this to
only rebuild the bits for CPUs we've actually installed new domains
on.
Reported-by: Ofer Levi(SW) <oferle@mellanox.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that we have more than one place to get the task state,
intruduce the task_state_to_char() helper function to save some code.
No functionality changed.
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <cj.chengjian@huawei.com>
Cc: <huawei.libin@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1502095463-160172-3-git-send-email-xiexiuqi@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently we print the runnable task in /proc/sched_debug, but
there is no task state information.
We don't know which task is in the runqueue and which task is sleeping.
Add task state in the runnable task list, like this:
runnable tasks:
S task PID tree-key switches prio wait-time sum-exec sum-sleep
-----------------------------------------------------------------------------------------------------------
S watchdog/239 1452 -11.917445 2811 0 0.000000 8.949306 0.000000 7 0 /
S migration/239 1453 20686.367740 8 0 0.000000 16215.720897 0.000000 7 0 /
S ksoftirqd/239 1454 115383.841071 12 120 0.000000 0.200683 0.000000 7 0 /
>R test 21287 4872.190970 407 120 0.000000 4874.911790 0.000000 7 0 /autogroup-150
R test 21288 4868.385454 401 120 0.000000 3672.341489 0.000000 7 0 /autogroup-150
R test 21289 4868.326776 384 120 0.000000 3424.934159 0.000000 7 0 /autogroup-150
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <cj.chengjian@huawei.com>
Cc: <huawei.libin@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1502095463-160172-2-git-send-email-xiexiuqi@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It appears as though the addition of the PID namespace did not update
the output code for /proc/*/sched, which resulted in it providing PIDs
that were not self-consistent with the /proc mount. This additionally
made it trivial to detect whether a process was inside &init_pid_ns from
userspace, making container detection trivial:
https://github.com/jessfraz/amicontained
This leads to situations such as:
% unshare -pmf
% mount -t proc proc /proc
% head -n1 /proc/1/sched
head (10047, #threads: 1)
Fix this by just using task_pid_nr_ns for the output of /proc/*/sched.
All of the other uses of task_pid_nr in kernel/sched/debug.c are from a
sysctl context and thus don't need to be namespaced.
Signed-off-by: Aleksa Sarai <asarai@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jess Frazelle <acidburn@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cyphar@cyphar.com
Link: http://lkml.kernel.org/r/20170806044141.5093-1-asarai@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add the value of the rt_rq.rt_nr_migratory and dl_rq.dl_nr_migratory
to the sched_debug output, for instance:
rt_rq[0]:
.rt_nr_running : 2
.rt_nr_migratory : 1 <--- Like this
.rt_throttled : 0
.rt_time : 828.645877
.rt_runtime : 1000.000000
This is useful to debug problems related to the RT/DL schedulers.
This also fixes the format of some variables, that were unsigned, rather
than signed.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>
Link: http://lkml.kernel.org/r/7896f71cada54ee7dd8507bb666063a2e051c3d4.1498482127.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
But first update the code that uses these facilities with the
new header.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Update code that relied on sched.h including various MM types for them.
This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch allows for reading the current (leftover) runtime and
absolute deadline of a SCHED_DEADLINE task through /proc/*/sched
(entries dl.runtime and dl.deadline), while debugging/testing.
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Acked-by: Daniel Bistrot de Oliveira <danielbristot@gmail.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1477473437-10346-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull cgroup updates from Tejun Heo:
- tracepoints for basic cgroup management operations added
- kernfs and cgroup path formatting functions updated to behave in the
style of strlcpy()
- non-critical bug fixes
* 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
blkcg: Unlock blkcg_pol_mutex only once when cpd == NULL
cgroup: fix error handling regressions in proc_cgroup_show() and cgroup_release_agent()
cpuset: fix error handling regression in proc_cpuset_show()
cgroup: add tracepoints for basic operations
cgroup: make cgroup_path() and friends behave in the style of strlcpy()
kernfs: remove kernfs_path_len()
kernfs: make kernfs_path*() behave in the style of strlcpy()
kernfs: add dummy implementation of kernfs_path_from_node()
The schedstat_val() macro's behavior is kind of surprising: when
schedstat is runtime disabled, it returns zero. Rename it to
schedstat_val_or_zero().
There's also a need for a similar macro which doesn't have the 'if
(schedstat_enable())' check, to avoid doing the check twice. Create a
new 'schedstat_val()' macro for that.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3bb1d2367d041fee333b0dde17171e709395b675.1466184592.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The schedstat_*() macros are inconsistent: most of them take a pointer
and a field which the macro combines, whereas schedstat_set() takes the
already combined ptr->field.
The already combined ptr->field argument is actually more intuitive and
easier to use, and there's no reason to require the user to split the
variable up, so convert the macros to use the combined argument.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/54953ca25bb579f3a5946432dee409b0e05222c6.1466184592.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
cgroup_path() and friends used to format the path from the end and
thus the resulting path usually didn't start at the start of the
passed in buffer. Also, when the buffer was too small, the partial
result was truncated from the head rather than tail and there was no
way to tell how long the full path would be. These make the functions
less robust and more awkward to use.
With recent updates to kernfs_path(), cgroup_path() and friends can be
made to behave in strlcpy() style.
* cgroup_path(), cgroup_path_ns[_locked]() and task_cgroup_path() now
always return the length of the full path. If buffer is too small,
it contains nul terminated truncated output.
* All users updated accordingly.
v2: cgroup_path() usage in kernel/sched/debug.c converted.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
The nr_migrations field is updated independently of CONFIG_SCHEDSTATS,
so it can be displayed regardless.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5b1b04057ae2b14d73c2d03f56582c1d38cfe066.1464994423.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit:
cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
... introduced a bug when CONFIG_SCHEDSTATS is enabled and the
runtime tunable is disabled (which is the default).
The wait-time, sum-exec, and sum-sleep fields are missing from the
/proc/sched_debug file in the runnable_tasks section.
Fix it with a new schedstat_val() macro which returns the field value
when schedstats is enabled and zero otherwise. The macro works with
both SCHEDSTATS and !SCHEDSTATS. I put the macro in stats.h since it
might end up being useful in other places.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/bcda7c2790cf2ccbe586a28c02dd7b6fe7749a2b.1464994423.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The max_idle_balance_cost and avg_idle values which are tracked and ar used to
capture short idle incidents, are not associated with schedstats, however the
information of these two values isn't printed out on !CONFIG_SCHEDSTATS kernels.
Fix this by moving the value printout out of the CONFIG_SCHEDSTATS section.
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1462250305-4523-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Playing with SCHED_DEADLINE and cpusets, I found that I was unable to create
new SCHED_DEADLINE tasks, with the error of EBUSY as if the bandwidth was
already used up. I then realized there wa no way to see what bandwidth is
used by the runqueues to debug the issue.
By adding the dl_bw->bw and dl_bw->total_bw to the output of the deadline
info in /proc/sched_debug, this allows us to see what bandwidth has been
reserved and where a problem may exist.
For example, before the issue we see the ratio of the bandwidth:
# cat /proc/sys/kernel/sched_rt_runtime_us
950000
# cat /proc/sys/kernel/sched_rt_period_us
1000000
# grep dl /proc/sched_debug
dl_rq[0]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[1]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[2]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[3]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[4]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[5]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[6]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[7]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
Note: (950000 / 1000000) << 20 == 996147
After I played with cpusets and hit the issue, the result is now:
# grep dl /proc/sched_debug
dl_rq[0]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[1]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 104857
dl_rq[2]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 104857
dl_rq[3]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 104857
dl_rq[4]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[5]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[6]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[7]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
This shows that there is definitely a problem as we should never have a
negative total bandwidth.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160222212825.756849091@goodmis.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The sched_domain_sysctl setup is only enabled when SCHED_DEBUG is
configured. As debug.c is only compiled when SCHED_DEBUG is configured as
well, move the setup of sched_domain_sysctl into that file.
Note, the (un)register_sched_domain_sysctl() functions had to be changed
from static to allow access to them from core.c.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160222212825.599278093@goodmis.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As /sys/kernel/debug/sched_features is only created when SCHED_DEBUG is enabled, and the file
debug.c is only compiled when SCHED_DEBUG is enabled, it makes sense to move
sched_feature setup into that file and get rid of the #ifdef.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160222212825.464193063@goodmis.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
schedstats is very useful during debugging and performance tuning but it
incurs overhead to calculate the stats. As such, even though it can be
disabled at build time, it is often enabled as the information is useful.
This patch adds a kernel command-line and sysctl tunable to enable or
disable schedstats on demand (when it's built in). It is disabled
by default as someone who knows they need it can also learn to enable
it when necessary.
The benefits are dependent on how scheduler-intensive the workload is.
If it is then the patch reduces the number of cycles spent calculating
the stats with a small benefit from reducing the cache footprint of the
scheduler.
These measurements were taken from a 48-core 2-socket
machine with Xeon(R) E5-2670 v3 cpus although they were also tested on a
single socket machine 8-core machine with Intel i7-3770 processors.
netperf-tcp
4.5.0-rc1 4.5.0-rc1
vanilla nostats-v3r1
Hmean 64 560.45 ( 0.00%) 575.98 ( 2.77%)
Hmean 128 766.66 ( 0.00%) 795.79 ( 3.80%)
Hmean 256 950.51 ( 0.00%) 981.50 ( 3.26%)
Hmean 1024 1433.25 ( 0.00%) 1466.51 ( 2.32%)
Hmean 2048 2810.54 ( 0.00%) 2879.75 ( 2.46%)
Hmean 3312 4618.18 ( 0.00%) 4682.09 ( 1.38%)
Hmean 4096 5306.42 ( 0.00%) 5346.39 ( 0.75%)
Hmean 8192 10581.44 ( 0.00%) 10698.15 ( 1.10%)
Hmean 16384 18857.70 ( 0.00%) 18937.61 ( 0.42%)
Small gains here, UDP_STREAM showed nothing intresting and neither did
the TCP_RR tests. The gains on the 8-core machine were very similar.
tbench4
4.5.0-rc1 4.5.0-rc1
vanilla nostats-v3r1
Hmean mb/sec-1 500.85 ( 0.00%) 522.43 ( 4.31%)
Hmean mb/sec-2 984.66 ( 0.00%) 1018.19 ( 3.41%)
Hmean mb/sec-4 1827.91 ( 0.00%) 1847.78 ( 1.09%)
Hmean mb/sec-8 3561.36 ( 0.00%) 3611.28 ( 1.40%)
Hmean mb/sec-16 5824.52 ( 0.00%) 5929.03 ( 1.79%)
Hmean mb/sec-32 10943.10 ( 0.00%) 10802.83 ( -1.28%)
Hmean mb/sec-64 15950.81 ( 0.00%) 16211.31 ( 1.63%)
Hmean mb/sec-128 15302.17 ( 0.00%) 15445.11 ( 0.93%)
Hmean mb/sec-256 14866.18 ( 0.00%) 15088.73 ( 1.50%)
Hmean mb/sec-512 15223.31 ( 0.00%) 15373.69 ( 0.99%)
Hmean mb/sec-1024 14574.25 ( 0.00%) 14598.02 ( 0.16%)
Hmean mb/sec-2048 13569.02 ( 0.00%) 13733.86 ( 1.21%)
Hmean mb/sec-3072 12865.98 ( 0.00%) 13209.23 ( 2.67%)
Small gains of 2-4% at low thread counts and otherwise flat. The
gains on the 8-core machine were slightly different
tbench4 on 8-core i7-3770 single socket machine
Hmean mb/sec-1 442.59 ( 0.00%) 448.73 ( 1.39%)
Hmean mb/sec-2 796.68 ( 0.00%) 794.39 ( -0.29%)
Hmean mb/sec-4 1322.52 ( 0.00%) 1343.66 ( 1.60%)
Hmean mb/sec-8 2611.65 ( 0.00%) 2694.86 ( 3.19%)
Hmean mb/sec-16 2537.07 ( 0.00%) 2609.34 ( 2.85%)
Hmean mb/sec-32 2506.02 ( 0.00%) 2578.18 ( 2.88%)
Hmean mb/sec-64 2511.06 ( 0.00%) 2569.16 ( 2.31%)
Hmean mb/sec-128 2313.38 ( 0.00%) 2395.50 ( 3.55%)
Hmean mb/sec-256 2110.04 ( 0.00%) 2177.45 ( 3.19%)
Hmean mb/sec-512 2072.51 ( 0.00%) 2053.97 ( -0.89%)
In constract, this shows a relatively steady 2-3% gain at higher thread
counts. Due to the nature of the patch and the type of workload, it's
not a surprise that the result will depend on the CPU used.
hackbench-pipes
4.5.0-rc1 4.5.0-rc1
vanilla nostats-v3r1
Amean 1 0.0637 ( 0.00%) 0.0660 ( -3.59%)
Amean 4 0.1229 ( 0.00%) 0.1181 ( 3.84%)
Amean 7 0.1921 ( 0.00%) 0.1911 ( 0.52%)
Amean 12 0.3117 ( 0.00%) 0.2923 ( 6.23%)
Amean 21 0.4050 ( 0.00%) 0.3899 ( 3.74%)
Amean 30 0.4586 ( 0.00%) 0.4433 ( 3.33%)
Amean 48 0.5910 ( 0.00%) 0.5694 ( 3.65%)
Amean 79 0.8663 ( 0.00%) 0.8626 ( 0.43%)
Amean 110 1.1543 ( 0.00%) 1.1517 ( 0.22%)
Amean 141 1.4457 ( 0.00%) 1.4290 ( 1.16%)
Amean 172 1.7090 ( 0.00%) 1.6924 ( 0.97%)
Amean 192 1.9126 ( 0.00%) 1.9089 ( 0.19%)
Some small gains and losses and while the variance data is not included,
it's close to the noise. The UMA machine did not show anything particularly
different
pipetest
4.5.0-rc1 4.5.0-rc1
vanilla nostats-v2r2
Min Time 4.13 ( 0.00%) 3.99 ( 3.39%)
1st-qrtle Time 4.38 ( 0.00%) 4.27 ( 2.51%)
2nd-qrtle Time 4.46 ( 0.00%) 4.39 ( 1.57%)
3rd-qrtle Time 4.56 ( 0.00%) 4.51 ( 1.10%)
Max-90% Time 4.67 ( 0.00%) 4.60 ( 1.50%)
Max-93% Time 4.71 ( 0.00%) 4.65 ( 1.27%)
Max-95% Time 4.74 ( 0.00%) 4.71 ( 0.63%)
Max-99% Time 4.88 ( 0.00%) 4.79 ( 1.84%)
Max Time 4.93 ( 0.00%) 4.83 ( 2.03%)
Mean Time 4.48 ( 0.00%) 4.39 ( 1.91%)
Best99%Mean Time 4.47 ( 0.00%) 4.39 ( 1.91%)
Best95%Mean Time 4.46 ( 0.00%) 4.38 ( 1.93%)
Best90%Mean Time 4.45 ( 0.00%) 4.36 ( 1.98%)
Best50%Mean Time 4.36 ( 0.00%) 4.25 ( 2.49%)
Best10%Mean Time 4.23 ( 0.00%) 4.10 ( 3.13%)
Best5%Mean Time 4.19 ( 0.00%) 4.06 ( 3.20%)
Best1%Mean Time 4.13 ( 0.00%) 4.00 ( 3.39%)
Small improvement and similar gains were seen on the UMA machine.
The gain is small but it stands to reason that doing less work in the
scheduler is a good thing. The downside is that the lack of schedstats and
tracepoints may be surprising to experts doing performance analysis until
they find the existence of the schedstats= parameter or schedstats sysctl.
It will be automatically activated for latencytop and sleep profiling to
alleviate the problem. For tracepoints, there is a simple warning as it's
not safe to activate schedstats in the context when it's known the tracepoint
may be wanted but is unavailable.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <mgalbraith@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1454663316-22048-1-git-send-email-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The cfs_rq's load_avg is composed of runnable_load_avg and blocked_load_avg.
Before this series, sometimes the runnable_load_avg is used, and sometimes
the load_avg is used. Completely replacing all uses of runnable_load_avg
with load_avg may be too big a leap, i.e., the blocked_load_avg is concerned
to result in overrated load. Therefore, we get runnable_load_avg back.
The new cfs_rq's runnable_load_avg is improved to be updated with all of the
runnable sched_eneities at the same time, so the one sched_entity updated and
the others stale problem is solved.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-7-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:
1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
updated at the granularity of an entity at a time, which results in the
cfs_rq's load average is stale or partially updated: at any time, only
one entity is up to date, all other entities are effectively lagging
behind. This is undesirable.
To illustrate, if we have n runnable entities in the cfs_rq, as time
elapses, they certainly become outdated:
t0: cfs_rq { e1_old, e2_old, ..., en_old }
and when we update:
t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
...
We solve this by combining all runnable entities' load averages together
in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
on the fact that if we regard the update as a function, then:
w * update(e) = update(w * e) and
update(e1) + update(e2) = update(e1 + e2), then
w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
therefore, by this rewrite, we have an entirely updated cfs_rq at the
time we update it:
t1: update cfs_rq { e1_new, e2_new, ..., en_new }
t2: update cfs_rq { e1_new, e2_new, ..., en_new }
...
2. cfs_rq's load average is different between top rq->cfs_rq and other
task_group's per CPU cfs_rqs in whether or not blocked_load_average
contributes to the load.
The basic idea behind runnable load average (the same for utilization)
is that the blocked state is taken into account as opposed to only
accounting for the currently runnable state. Therefore, the average
should include both the runnable/running and blocked load averages.
This rewrite does that.
In addition, we also combine runnable/running and blocked averages
of all entities into the cfs_rq's average, and update it together at
once. This is based on the fact that:
update(runnable) + update(blocked) = update(runnable + blocked)
This significantly reduces the code as we don't need to separately
maintain/update runnable/running load and blocked load.
3. How task_group entities' share is calculated is complex and imprecise.
We reduce the complexity in this rewrite to allow a very simple rule:
the task_group's load_avg is aggregated from its per CPU cfs_rqs's
load_avgs. Then group entity's weight is simply proportional to its
own cfs_rq's load_avg / task_group's load_avg. To illustrate,
if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.
As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 44dba3d5d6 ("sched: Refactor task_struct to use
numa_faults instead of numa_* pointers") modified the way
tsk->numa_faults stats are accounted.
However that commit never touched show_numa_stats() that is displayed
in /proc/pid/sched and thus the numbers displayed in /proc/pid/sched
don't match the actual numbers.
Fix it by making sure that /proc/pid/sched reflects the task
fault numbers. Also add group fault stats too.
Also couple of more modifications are added here:
1. Format changes:
- Previously we would list two entries per node, one for private
and one for shared. Also the home node info was listed in each entry.
- Now preferred node, total_faults and current node are
displayed separately.
- Now there is one entry per node, that lists private,shared task and
group faults.
2. Unit changes:
- p->numa_pages_migrated was getting reset after every read of
/proc/pid/sched. It's more useful to have absolute numbers since
differential migrations between two accesses can be more easily
calculated.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Iulia Manda <iulia.manda21@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435252903-1081-4-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Having the numa group ID in /proc/sched_debug helps to see how
the numa groups have spread across the system.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Iulia Manda <iulia.manda21@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435252903-1081-3-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull timer updates from Thomas Gleixner:
"A rather largish update for everything time and timer related:
- Cache footprint optimizations for both hrtimers and timer wheel
- Lower the NOHZ impact on systems which have NOHZ or timer migration
disabled at runtime.
- Optimize run time overhead of hrtimer interrupt by making the clock
offset updates smarter
- hrtimer cleanups and removal of restrictions to tackle some
problems in sched/perf
- Some more leap second tweaks
- Another round of changes addressing the 2038 problem
- First step to change the internals of clock event devices by
introducing the necessary infrastructure
- Allow constant folding for usecs/msecs_to_jiffies()
- The usual pile of clockevent/clocksource driver updates
The hrtimer changes contain updates to sched, perf and x86 as they
depend on them plus changes all over the tree to cleanup API changes
and redundant code, which got copied all over the place. The y2038
changes touch s390 to remove the last non 2038 safe code related to
boot/persistant clock"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (114 commits)
clocksource: Increase dependencies of timer-stm32 to limit build wreckage
timer: Minimize nohz off overhead
timer: Reduce timer migration overhead if disabled
timer: Stats: Simplify the flags handling
timer: Replace timer base by a cpu index
timer: Use hlist for the timer wheel hash buckets
timer: Remove FIFO "guarantee"
timers: Sanitize catchup_timer_jiffies() usage
hrtimer: Allow hrtimer::function() to free the timer
seqcount: Introduce raw_write_seqcount_barrier()
seqcount: Rename write_seqcount_barrier()
hrtimer: Fix hrtimer_is_queued() hole
hrtimer: Remove HRTIMER_STATE_MIGRATE
selftest: Timers: Avoid signal deadlock in leap-a-day
timekeeping: Copy the shadow-timekeeper over the real timekeeper last
clockevents: Check state instead of mode in suspend/resume path
selftests: timers: Add leap-second timer edge testing to leap-a-day.c
ntp: Do leapsecond adjustment in adjtimex read path
time: Prevent early expiry of hrtimers[CLOCK_REALTIME] at the leap second edge
ntp: Introduce and use SECS_PER_DAY macro instead of 86400
...
When CONFIG_SCHEDSTATS is enabled, /proc/<pid>/sched prints almost all
sched statistics except sum_sleep_runtime. Since sum_sleep_runtime is
a good info to collect, add this it to /proc/<pid>/sched.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1433751041-11724-4-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Colin Ian King
Hidetoshi Seto
Masahiro Yamada
Viresh Kumar
Jiada Wang
Linus Torvalds
Srikar Dronamraju
Pavel Tatashin
Yisheng Xie
Christoph Hellwig
Joe Lawrence
Patrick Bellasi
Ingo Molnar
Peter Zijlstra
Davidlohr Bueso
Xie XiuQi
Aleksa Sarai
Daniel Bristot de Oliveira
Tommaso Cucinotta
Josh Poimboeuf
Tejun Heo
Wanpeng Li
Steven Rostedt (Red Hat)
Mel Gorman
Yuyang Du