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Barry Song d0637c505f arm64: enable THP_SWAP for arm64
THP_SWAP has been proven to improve the swap throughput significantly
on x86_64 according to commit bd4c82c22c ("mm, THP, swap: delay
splitting THP after swapped out").
As long as arm64 uses 4K page size, it is quite similar with x86_64
by having 2MB PMD THP. THP_SWAP is architecture-independent, thus,
enabling it on arm64 will benefit arm64 as well.
A corner case is that MTE has an assumption that only base pages
can be swapped. We won't enable THP_SWAP for ARM64 hardware with
MTE support until MTE is reworked to coexist with THP_SWAP.

A micro-benchmark is written to measure thp swapout throughput as
below,

 unsigned long long tv_to_ms(struct timeval tv)
 {
 	return tv.tv_sec * 1000 + tv.tv_usec / 1000;
 }

 main()
 {
 	struct timeval tv_b, tv_e;;
 #define SIZE 400*1024*1024
 	volatile void *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE,
 				MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 	if (!p) {
 		perror("fail to get memory");
 		exit(-1);
 	}

 	madvise(p, SIZE, MADV_HUGEPAGE);
 	memset(p, 0x11, SIZE); /* write to get mem */

 	gettimeofday(&tv_b, NULL);
 	madvise(p, SIZE, MADV_PAGEOUT);
 	gettimeofday(&tv_e, NULL);

 	printf("swp out bandwidth: %ld bytes/ms\n",
 			SIZE/(tv_to_ms(tv_e) - tv_to_ms(tv_b)));
 }

Testing is done on rk3568 64bit Quad Core Cortex-A55 platform -
ROCK 3A.
thp swp throughput w/o patch: 2734bytes/ms (mean of 10 tests)
thp swp throughput w/  patch: 3331bytes/ms (mean of 10 tests)

Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Link: https://lore.kernel.org/r/20220720093737.133375-1-21cnbao@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
2022-07-20 10:52:40 +01:00
Documentation A set of interrupt subsystem updates: 2022-06-19 09:45:16 -05:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch arm64: enable THP_SWAP for arm64 2022-07-20 10:52:40 +01:00
block block/bfq: Enable I/O statistics 2022-06-16 16:59:28 -06:00
certs certs: fix and refactor CONFIG_SYSTEM_BLACKLIST_HASH_LIST build 2022-06-15 21:52:32 +03:00
crypto crypto: memneq - move into lib/ 2022-06-12 14:51:51 +08:00
drivers A set of interrupt subsystem updates: 2022-06-19 09:45:16 -05:00
fs Fixes for 5.19-rc3: 2022-06-19 09:24:49 -05:00
include arm64: enable THP_SWAP for arm64 2022-07-20 10:52:40 +01:00
init gcc-12: disable '-Warray-bounds' universally for now 2022-06-09 10:11:12 -07:00
ipc These changes update the ipc sysctls so that they are fundamentally 2022-06-03 15:54:57 -07:00
kernel A single scheduler fix plugging a race between sched_setscheduler() and 2022-06-19 09:51:00 -05:00
lib Build tool updates: 2022-06-19 09:54:16 -05:00
mm arm64: enable THP_SWAP for arm64 2022-07-20 10:52:40 +01:00
net NFS Client Fixes for Linux 5.19-rc 2022-06-17 15:17:57 -05:00
samples drm for 5.19-rc1 2022-05-25 16:18:27 -07:00
scripts Build tool updates: 2022-06-19 09:54:16 -05:00
security selinux: free contexts previously transferred in selinux_add_opt() 2022-06-15 21:20:45 -04:00
sound sound fixes for 5.19-rc2 2022-06-10 10:20:57 -07:00
tools Build tool updates: 2022-06-19 09:54:16 -05:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: x86: disable preemption around the call to kvm_arch_vcpu_{un|}blocking 2022-06-09 10:52:20 -04:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap Hot fixes for 5.19-rc1. 2022-06-05 17:05:38 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS rectifications and a few minor driver fixes 2022-06-19 09:35:09 -05:00
Makefile Linux 5.19-rc3 2022-06-19 15:06:47 -05:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.