linux-kernel - [PATCH 0/2] x86/idle: add halt poll support

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Message-Id: <1498130534-26568-1-git-send-email-root@ip-172-31-39-62.us-west-2.compute.internal>
Date:   Thu, 22 Jun 2017 11:22:12 +0000
From:   root <yang.zhang.wz@...il.com>
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Subject: [PATCH 0/2] x86/idle: add halt poll support

From: Yang Zhang <yang.zhang.wz@...il.com>

Some latency-intensive workload will see obviously performance
drop when running inside VM. The main reason is that the overhead
is amplified when running inside VM. The most cost i have seen is
inside idle path.
This patch introduces a new mechanism to poll for a while before
entering idle state. If schedule is needed during poll, then we 
don't need to goes through the heavy overhead path.

Here is the data i get when running benchmark contextswitch
(https://github.com/tsuna/contextswitch)
before patch:
2000000 process context switches in 4822613801ns (2411.3ns/ctxsw)
after patch:
2000000 process context switches in 3584098241ns (1792.0ns/ctxsw)


Yang Zhang (2):
  x86/idle: add halt poll for halt idle
  x86/idle: use dynamic halt poll

 Documentation/sysctl/kernel.txt          | 24 ++++++++++
 arch/x86/include/asm/processor.h         |  6 +++
 arch/x86/kernel/apic/apic.c              |  6 +++
 arch/x86/kernel/apic/vector.c            |  1 +
 arch/x86/kernel/cpu/mcheck/mce_amd.c     |  2 +
 arch/x86/kernel/cpu/mcheck/therm_throt.c |  2 +
 arch/x86/kernel/cpu/mcheck/threshold.c   |  2 +
 arch/x86/kernel/irq.c                    |  5 ++
 arch/x86/kernel/irq_work.c               |  2 +
 arch/x86/kernel/process.c                | 80 ++++++++++++++++++++++++++++++++
 arch/x86/kernel/smp.c                    |  6 +++
 include/linux/kernel.h                   |  5 ++
 kernel/sched/idle.c                      |  3 ++
 kernel/sysctl.c                          | 23 +++++++++
 14 files changed, 167 insertions(+)

-- 
1.8.3.1