Re: [PATCH] sched: fix env->src_cpu for active migration

From: Vincent Guittot
Date: Wed Feb 13 2013 - 12:49:12 EST

On 13 February 2013 15:28, Vincent Guittot <vincent.guittot@xxxxxxxxxx> wrote:
> On 13 February 2013 15:08, Damien Wyart <damien.wyart@xxxxxxxxx> wrote:
>> * Vincent Guittot <vincent.guittot@xxxxxxxxxx> [2013-02-13 13:08]:
>>> Damien,
>>> Regarding your sched_domain config and especially the flags field, you
>>> should not be impacted by my patch because
>>> - need_active_balance is the only new place that use env->src_cpu in
>>> the load_balance function
>>> - and your machine will never test the condition: "env->src_cpu >
>>> env->dst_cpu" in need_active_balance because SD_ASYM_PACKING is not
>>> set in your config
>>> Have you tested the patch with others that could have modified the
>>> load_balance function ?
>> Yes, sorry, I should have been more precise in my initial report: your
>> patch was not applied on top of vanilla 3.8-rc7, but a few other patches
>> were also present. Seems the ones impacting load_balance are from
>> Frederic's nohz work
>> (;a=shortlog;h=refs/heads/3.8-rc6-nohz4)
> ok
> thanks for the pointer. i'm going to have a look
>> The patches from there modifying load_balance are:
>> - "sched: Update nohz rq clock before searching busiest group on load balancing"
>> - "sched: Update clock of nohz busiest rq before balancing"
>> In this test, I did not use any kernel parameter related to this
>> patchset (full_nohz, etc.).
>> I am adding Frederic in Cc, not sure if the breakage is to be
>> investigated on your side or his...
> probably both

I have look into Frederic's tree but i didn't find any reason that
could explain your problem. May be Frederic will have some ideas
I have also tested his branch with and without my patch and both
kernel are booting (on an ARM platform without using the full_nohz
feature ).
I have faced a conflict when i have applied my patch on his branch as
we insert code at the same place. You should have faced the same
conflict. How have you solved it ?

>> Thanks for your explanations,
>> --
>> Damien
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