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  1. 14 4月, 2009 2 次提交
    • G
      sched: Nominate a power-efficient ilb in select_nohz_balancer() · e790fb0b
      由 Gautham R Shenoy 提交于 
      The CPU that first goes idle becomes the idle-load-balancer and remains
that until either it picks up a task or till all the CPUs of the system
goes idle.

Optimize this further to allow it to relinquish it's post
once all it's siblings in the power-aware sched_domain go idle, thereby
allowing the whole package-core to go idle. While relinquising the post,
nominate another an idle-load balancer from a semi-idle core/package.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090414045535.7645.31641.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e790fb0b
    • G
      sched: Nominate idle load balancer from a semi-idle package. · f711f609
      由 Gautham R Shenoy 提交于 
      Currently the nomination of idle-load balancer is done by choosing the first
idle cpu in the nohz.cpu_mask. This may not be power-efficient, since
such an idle cpu could come from a completely idle core/package thereby
preventing the whole core/package from being in a low-power state.

For eg, consider a quad-core dual package system. The cpu numbering need
not be sequential and can something like [0, 2, 4, 6] and [1, 3, 5, 7].
With sched_mc/smt_power_savings and the power-aware IRQ balance, we try to keep
as fewer Packages/Cores active. But the current idle load balancer logic
goes against this by choosing the first_cpu in the nohz.cpu_mask and not
taking the system topology into consideration.

Improve the algorithm to nominate the idle load balancer from a semi idle
cores/packages thereby increasing the probability of the cores/packages being
in deeper sleep states for longer duration.

The algorithm is activated only when sched_mc/smt_power_savings != 0.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090414045530.7645.12175.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      f711f609
  3. 09 4月, 2009 2 次提交
    • P
      sched: remove redundant hierarchy walk in check_preempt_wakeup · 002f128b
      由 Paul Turner 提交于 
      Impact: micro-optimization

Under group scheduling we traverse up until we are at common siblings
to make the wakeup comparison on.

At this point however, they should have the same parent so continuing
to check up the tree is redundant.
Signed-off-by: NPaul Turner <pjt@google.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <alpine.DEB.1.00.0904081520320.30317@kitami.corp.google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      002f128b
    • N
      sched: do not count frozen tasks toward load · e3c8ca83
      由 Nathan Lynch 提交于 
      Freezing tasks via the cgroup freezer causes the load average to climb
because the freezer's current implementation puts frozen tasks in
uninterruptible sleep (D state).

Some applications which perform job-scheduling functions consult the
load average when making decisions.  If a cgroup is frozen, the load
average does not provide a useful measure of the system's utilization
to such applications.  This is especially inconvenient if the job
scheduler employs the cgroup freezer as a mechanism for preempting low
priority jobs.  Contrast this with using SIGSTOP for the same purpose:
the stopped tasks do not count toward system load.

Change task_contributes_to_load() to return false if the task is
frozen.  This results in /proc/loadavg behavior that better meets
users' expectations.
Signed-off-by: NNathan Lynch <ntl@pobox.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NNigel Cunningham <nigel@tuxonice.net>
Tested-by: NNigel Cunningham <nigel@tuxonice.net>
Cc: <stable@kernel.org>
Cc: containers@lists.linux-foundation.org
Cc: linux-pm@lists.linux-foundation.org
Cc: Matt Helsley <matthltc@us.ibm.com>
LKML-Reference: <20090408194512.47a99b95@manatee.lan>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e3c8ca83
  5. 08 4月, 2009 10 次提交
  7. 07 4月, 2009 26 次提交