linux/arch
Lan Tianyu 2ed53c0d6c x86/smpboot: Speed up suspend/resume by avoiding 100ms sleep for CPU offline during S3
With certain kernel configurations, CPU offline consumes more than
100ms during S3.

It's a timing related issue: native_cpu_die() would occasionally fall
into a 100ms sleep when the CPU idle loop thread marked the CPU state
to DEAD too slowly.

What native_cpu_die() does is that it polls the CPU state and waits
for 100ms if CPU state hasn't been marked to DEAD. The 100ms sleep
doesn't make sense and is purely historic.

To avoid such long sleeping, this patch adds a 'struct completion'
to each CPU, waits for the completion in native_cpu_die() and wakes
up the completion when the CPU state is marked to DEAD.

Tested on an Intel Xeon server with 48 cores, Ivybridge and on
Haswell laptops. The CPU offlining cost on these machines is
reduced from more than 100ms to less than 5ms. The system
suspend time is reduced by 2.3s on the servers.

Borislav and Prarit also helped to test the patch on an AMD
machine and a few systems of various sizes and configurations
(multi-socket, single-socket, no hyper threading, etc.). No
issues were seen.

Tested-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: srostedt@redhat.com
Cc: toshi.kani@hp.com
Cc: imammedo@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409039025-32310-1-git-send-email-tianyu.lan@intel.com
[ Improved a few minor details in the code, cleaned up the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 15:02:06 +02:00
..
alpha alpha: io: implement relaxed accessor macros for writes 2014-08-29 11:18:45 -07:00
arc ARC: [mm] Fix compilation breakage 2014-09-03 10:08:50 -07:00
arm Merge branch 'fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2014-09-21 12:11:52 -07:00
arm64 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-09-19 09:07:47 -07:00
avr32 Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
blackfin Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
c6x Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
cris Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
frv frv: Define cpu_relax_lowlatency() 2014-08-19 09:40:08 -05:00
hexagon flush_icache_range: export symbol to fix build errors 2014-08-29 16:28:17 -07:00
ia64 PCI updates for v3.17: 2014-09-19 10:50:30 -07:00
m32r Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
m68k m68k: Wire up memfd_create 2014-09-01 10:28:00 +02:00
metag Metag architecture changes for v3.17 2014-08-13 18:18:09 -06:00
microblaze microblaze: Fix number of syscalls 2014-09-09 13:14:47 +02:00
mips Two very simple bugfixes, affecting all supported architectures. 2014-09-22 11:58:23 -07:00
mn10300 Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
openrisc Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
parisc parisc: Implement new LWS CAS supporting 64 bit operations. 2014-09-13 22:40:48 +02:00
powerpc powerpc: Wire up sys_seccomp(), sys_getrandom() and sys_memfd_create() 2014-09-09 19:02:47 +10:00
s390 Two very simple bugfixes, affecting all supported architectures. 2014-09-22 11:58:23 -07:00
score Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
sh sh: get_user_pages_fast() must flush cache 2014-09-10 15:42:12 -07:00
sparc sparc: bpf_jit: fix support for ldx/stx mem and SKF_AD_VLAN_TAG 2014-09-19 16:01:18 -04:00
tile flush_icache_range: export symbol to fix build errors 2014-08-29 16:28:17 -07:00
um Merge branch 'signal-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc 2014-08-09 09:58:12 -07:00
unicore32 unicore32: Fix build error 2014-08-31 17:08:12 -07:00
x86 x86/smpboot: Speed up suspend/resume by avoiding 100ms sleep for CPU offline during S3 2014-09-24 15:02:06 +02:00
xtensa Xtensa improvements for 3.17: 2014-08-31 17:08:42 -07:00
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