Re: Kernel 4.7rc3 - Performance drop 30-40% for SPECjbb2005 and SPECjvm2008 benchmarks against 4.6 kernel

[Jirka Hladky]

OK, I have applied to v4.7-rc4 via git am

Compiling kernel, should have the results soon.

Jirka

On Fri, Jun 24, 2016 at 2:09 PM, Jirka Hladky <jhladky@xxxxxxxxxx> wrote:
> Thank you Peter!
>
> Should I apply it to v4.7-rc4 ?
>
> Jirka
>
> On Fri, Jun 24, 2016 at 2:02 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>> On Fri, Jun 24, 2016 at 09:44:41AM +0200, Jirka Hladky wrote:
>>> Hi Peter,
>>>
>>> thanks a lot for looking into it!
>>>
>>> I have tried to disable autogroups
>>>
>>> sysctl -w kernel.sched_autogroup_enabled=0
>>>
>>> and I can confirm that performance is then back at level as in 4.6 kernel.
>>
>> So unless the heat has made me do really silly things, the below seems
>> to cure things. Could you please verify?
>>
>>
>> ---
>>  kernel/sched/fair.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 22d64b3f5876..d4f6fb2f3057 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -2484,7 +2484,7 @@ static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
>>          */
>>         tg_weight = atomic_long_read(&tg->load_avg);
>>         tg_weight -= cfs_rq->tg_load_avg_contrib;
>> -       tg_weight += cfs_rq->load.weight;
>> +       tg_weight += cfs_rq->avg.load_avg;
>>
>>         return tg_weight;
>>  }
>> @@ -2494,7 +2494,7 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
>>         long tg_weight, load, shares;
>>
>>         tg_weight = calc_tg_weight(tg, cfs_rq);
>> -       load = cfs_rq->load.weight;
>> +       load = cfs_rq->avg.load_avg;
>>
>>         shares = (tg->shares * load);
>>         if (tg_weight)