82 строки
2.9 KiB
Plaintext
82 строки
2.9 KiB
Plaintext
|
|
Export cpu topology info via sysfs. Items (attributes) are similar
|
|
to /proc/cpuinfo.
|
|
|
|
1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
|
|
represent the physical package id of cpu X;
|
|
2) /sys/devices/system/cpu/cpuX/topology/core_id:
|
|
represent the cpu core id to cpu X;
|
|
3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
|
|
represent the thread siblings to cpu X in the same core;
|
|
4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
|
|
represent the thread siblings to cpu X in the same physical package;
|
|
|
|
To implement it in an architecture-neutral way, a new source file,
|
|
drivers/base/topology.c, is to export the 4 attributes.
|
|
|
|
For an architecture to support this feature, it must define some of
|
|
these macros in include/asm-XXX/topology.h:
|
|
#define topology_physical_package_id(cpu)
|
|
#define topology_core_id(cpu)
|
|
#define topology_thread_cpumask(cpu)
|
|
#define topology_core_cpumask(cpu)
|
|
|
|
The type of **_id is int.
|
|
The type of siblings is (const) struct cpumask *.
|
|
|
|
To be consistent on all architectures, include/linux/topology.h
|
|
provides default definitions for any of the above macros that are
|
|
not defined by include/asm-XXX/topology.h:
|
|
1) physical_package_id: -1
|
|
2) core_id: 0
|
|
3) thread_siblings: just the given CPU
|
|
4) core_siblings: just the given CPU
|
|
|
|
Additionally, cpu topology information is provided under
|
|
/sys/devices/system/cpu and includes these files. The internal
|
|
source for the output is in brackets ("[]").
|
|
|
|
kernel_max: the maximum cpu index allowed by the kernel configuration.
|
|
[NR_CPUS-1]
|
|
|
|
offline: cpus that are not online because they have been
|
|
HOTPLUGGED off (see cpu-hotplug.txt) or exceed the limit
|
|
of cpus allowed by the kernel configuration (kernel_max
|
|
above). [~cpu_online_mask + cpus >= NR_CPUS]
|
|
|
|
online: cpus that are online and being scheduled [cpu_online_mask]
|
|
|
|
possible: cpus that have been allocated resources and can be
|
|
brought online if they are present. [cpu_possible_mask]
|
|
|
|
present: cpus that have been identified as being present in the
|
|
system. [cpu_present_mask]
|
|
|
|
The format for the above output is compatible with cpulist_parse()
|
|
[see <linux/cpumask.h>]. Some examples follow.
|
|
|
|
In this example, there are 64 cpus in the system but cpus 32-63 exceed
|
|
the kernel max which is limited to 0..31 by the NR_CPUS config option
|
|
being 32. Note also that cpus 2 and 4-31 are not online but could be
|
|
brought online as they are both present and possible.
|
|
|
|
kernel_max: 31
|
|
offline: 2,4-31,32-63
|
|
online: 0-1,3
|
|
possible: 0-31
|
|
present: 0-31
|
|
|
|
In this example, the NR_CPUS config option is 128, but the kernel was
|
|
started with possible_cpus=144. There are 4 cpus in the system and cpu2
|
|
was manually taken offline (and is the only cpu that can be brought
|
|
online.)
|
|
|
|
kernel_max: 127
|
|
offline: 2,4-127,128-143
|
|
online: 0-1,3
|
|
possible: 0-127
|
|
present: 0-3
|
|
|
|
See cpu-hotplug.txt for the possible_cpus=NUM kernel start parameter
|
|
as well as more information on the various cpumask's.
|