sched, cpuacct: refactoring cpuusage_read / cpuusage_write

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Impact: micro-optimize the code on 64-bit architectures

In the thread regarding to 'export percpu cpuacct cgroup stats'
http://lkml.org/lkml/2008/12/7/13

akpm pointed out that current cpuacct code is inefficient.  This patch
refactoring the following:

* make cpu_rq locking only on 32-bit
* change iterator to each_present_cpu instead of each_possible_cpu to
  make it hotplug friendly.

It's a bit of code churn, but I was rewarded with 160 byte code size saving
on x86-64 arch and zero code size change on i386.

Signed-off-by: Ken Chen <kenchen@google.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

...

This commit is contained in:

Ken Chen 2008-12-15 22:02:01 -08:00 • committed by Ingo Molnar

parent 34f28ecd0f

commit 720f54988e

1 changed files with 39 additions and 17 deletions

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kernel/sched.c

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