Re: [tip:sched/core] sched/balancing: Fix cfs_rq-> task_h_load calculation

From: Vladimir Davydov
Date: Mon Sep 30 2013 - 04:14:28 EST

On 09/29/2013 01:47 PM, Yuanhan Liu wrote:
On Fri, Sep 20, 2013 at 06:46:59AM -0700, tip-bot for Vladimir Davydov wrote:
Commit-ID: 7e3115ef5149fc502e3a2e80719dba54a8e7409d
Author: Vladimir Davydov<vdavydov@xxxxxxxxxxxxx>
AuthorDate: Sat, 14 Sep 2013 19:39:46 +0400
Committer: Ingo Molnar<mingo@xxxxxxxxxx>
CommitDate: Fri, 20 Sep 2013 11:59:39 +0200

sched/balancing: Fix cfs_rq->task_h_load calculation

Patch a003a2 (sched: Consider runnable load average in move_tasks())
sets all top-level cfs_rqs' h_load to rq->avg.load_avg_contrib, which is
always 0. This mistype leads to all tasks having weight 0 when load
balancing in a cpu-cgroup enabled setup. There obviously should be sum
of weights of all runnable tasks there instead. Fix it.
Hi Vladimir,

FYI, Here we found a 17% netperf regression by this patch. Here are some
changed stats between this commit 7e3115ef5149fc502e3a2e80719dba54a8e7409d
and it's parent(3029ede39373c368f402a76896600d85a4f7121b)


Could you please report the following info:

1) the test machine cpu topology (i.e. output of /sys/devices/system/cpu/cpu*/{thread_siblings_list,core_siblings_list})
2) kernel config you used during the test
3) the output of /sys/kernel/debug/sched_features (debugfs mounted).
4) netperf server/client options
5) did you place netserver into a separate cpu cgroup?

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