From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Bruno Wolff III <bruno@wolff.to>
Cc: Josh Boyer <jwboyer@redhat.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Scheduler regression from caffcdd8d27ba78730d5540396ce72ad022aff2c
Date: Thu, 17 Jul 2014 10:57:55 +0200 [thread overview]
Message-ID: <53C79013.1020808@arm.com> (raw)
In-Reply-To: <20140717030947.GA17889@wolff.to>
On 17/07/14 05:09, Bruno Wolff III wrote:
> On Thu, Jul 17, 2014 at 01:18:36 +0200,
> Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>> So the output of
>>
>> $ cat /proc/sys/kernel/sched_domain/cpu*/domain*/*
>>
>> would be handy too.
Thanks, this was helpful.
I see from the sched domain layout that you have SMT (domain0) and DIE
(domain1) level. So on this system, the MC level gets degenerated
(sd_degenerate() in kernel/sched/core.c).
I fail so far to see how this can have an effect on the memory of the
sched groups. But I can try to fake this situation on one of my platforms.
There is also the possibility that the memory for sched_group sg is not
(completely) zeroed out:
sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
struct sched_group {
...
* NOTE: this field is variable length. (Allocated dynamically
* by attaching extra space to the end of the structure,
* depending on how many CPUs the kernel has booted up with)
*/
unsigned long cpumask[0];
};
so that the cpumask of a sched group is not 0 and can only be cured by
an explicit cpumask_clear(sched_group_cpus(sg)) in build_sched_groups()
on this kind of machine.
>
> Attached and added to the bug.
>
>> Just to make sure, you do have 'CONFIG_X86_32=y' and '# CONFIG_NUMA is
>> not set' in your build?
>
> Yes.
>
> I probably won't be able to get /proc/schedstat on my next test since the
> system will probably crash right away. However, I probably will have a
> much faster rebuild and might still be able to get the info for you
> before I leave tomorrow.
>
next prev parent reply other threads:[~2014-07-17 8:58 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-16 14:55 Scheduler regression from caffcdd8d27ba78730d5540396ce72ad022aff2c Bruno Wolff III
2014-07-16 15:17 ` Josh Boyer
2014-07-16 19:17 ` Dietmar Eggemann
2014-07-16 19:54 ` Bruno Wolff III
2014-07-16 23:18 ` Dietmar Eggemann
2014-07-17 3:09 ` Bruno Wolff III
2014-07-17 8:57 ` Dietmar Eggemann [this message]
2014-07-17 9:04 ` Peter Zijlstra
2014-07-17 11:23 ` Dietmar Eggemann
2014-07-17 12:35 ` Peter Zijlstra
2014-07-18 5:34 ` Bruno Wolff III
2014-07-18 9:28 ` Dietmar Eggemann
2014-07-18 12:09 ` Bruno Wolff III
2014-07-18 10:16 ` Peter Zijlstra
2014-07-18 13:01 ` Bruno Wolff III
2014-07-18 14:16 ` Dietmar Eggemann
2014-07-18 14:16 ` Peter Zijlstra
2014-07-18 14:50 ` Peter Zijlstra
2014-07-18 16:16 ` Peter Zijlstra
2014-07-21 16:35 ` Bruno Wolff III
2014-07-21 16:52 ` Peter Zijlstra
2014-07-22 9:47 ` Peter Zijlstra
2014-07-22 10:38 ` Peter Zijlstra
2014-07-22 12:10 ` Bruno Wolff III
2014-07-22 13:03 ` Peter Zijlstra
2014-07-22 13:26 ` Peter Zijlstra
2014-07-22 13:35 ` Peter Zijlstra
2014-07-22 14:09 ` Bruno Wolff III
2014-07-22 14:18 ` Peter Zijlstra
2014-07-23 1:37 ` Bruno Wolff III
2014-07-23 6:51 ` Peter Zijlstra
2014-07-22 17:05 ` H. Peter Anvin
2014-07-23 15:11 ` Peter Zijlstra
2014-07-23 15:12 ` H. Peter Anvin
2014-07-24 1:45 ` Bruno Wolff III
2014-07-23 15:39 ` [tip:x86/urgent] x86, cpu: Fix cache topology for early P4-SMT tip-bot for Peter Zijlstra
2014-07-22 12:12 ` Scheduler regression from caffcdd8d27ba78730d5540396ce72ad022aff2c Dietmar Eggemann
2014-07-22 12:57 ` Bruno Wolff III
2014-07-28 8:28 ` [tip:sched/core] sched: Robustify topology setup tip-bot for Peter Zijlstra
2014-07-17 16:36 ` Scheduler regression from caffcdd8d27ba78730d5540396ce72ad022aff2c Bruno Wolff III
2014-07-17 18:43 ` Dietmar Eggemann
2014-07-17 18:54 ` Bruno Wolff III
2014-07-17 4:21 ` Bruno Wolff III
2014-07-17 4:28 ` Bruno Wolff III
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