linux-kernel - Re: [PATCH] Do not include throttled time as steal time

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Message-ID: <4EDCFA1C.3050105@linux.vnet.ibm.com>
Date:	Mon, 05 Dec 2011 11:06:36 -0600
From:	Mike wolf <mjw@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	linux-kernel@...r.kernel.org, paulmck <paulmck@...ux.vnet.ibm.com>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>, Paul Turner <pjt@...gle.com>
Subject: Re: [PATCH] Do not include throttled time as steal time

On 12/05/2011 10:20 AM, Peter Zijlstra wrote:
> On Mon, 2011-12-05 at 09:08 -0600, Mike wolf wrote:
>
> Hi Mike, couple of problems with this:
>
> 1) You failed to CC the appropriate maintainers for the piece of code
> you're trying to have changed. When in doubt see the MAINTAINERS
> file ;-)
yes will do
> 2) You failed to CC the people who wrote the feature you're having a
> problem with.
ok, I will add Glauber and others when the patch is respun/resubmitted
>> When the linux kernel is running as the guest OS and is configured
>> for bandwidth control and steal time reporting, it can be confusing
>> to users to see the throttled time show up in the steal time stats.
>> The user will think they are not getting the cpu resources they have
>> been configured.
> Supposedly this is a BAD (tm) thing :-)
>
>> Signed-off-by: Mike Wolf<mjw@...ux.vnet.ibm.com>
>> ---
>>    kernel/sched_fair.c  |    4 ++--
>>    kernel/sched_stats.h |    7 ++++++-
>>    2 files changed, 8 insertions(+), 3 deletions(-)
> 3) You blink you loose, those files don't exist anymore. Patches are
> best provided against the development tree of the particular subsystem
> you're working against.
>
> In this particular case tip/master is your target.
>
>>    static inline void sched_info_depart(struct task_struct *t)
>>    {
>> +    struct task_group *tg = task_group(t);
>> +    struct cfs_rq *cfs_rq;
>>        unsigned long long delta = task_rq(t)->clock -
>>                        t->sched_info.last_arrival;
>>
>> +    cfs_rq = tg->cfs_rq[smp_processor_id()];
>>        rq_sched_info_depart(task_rq(t), delta);
>>
>> -    if (t->state == TASK_RUNNING)
>> +
>> +    if (t->state == TASK_RUNNING&&  !throttled_hierarchy(cfs_rq))
>>            sched_info_queued(t);
>>    }
> 4) so there's a lot more steal time crap all over the scheduler, you
> failed to explain why only this particular bit is important enough to
> change.
I will make sure to explain why you would want the patch functionality 
better
when I resubmit.
>
>

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