From: Jason Baron <jbaron@akamai.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@redhat.com, viro@zeniv.linux.org.uk,
akpm@linux-foundation.org, normalperson@yhbt.net,
davidel@xmailserver.org, mtk.manpages@gmail.com,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 1/2] sched/wait: add round robin wakeup mode
Date: Mon, 09 Feb 2015 23:06:17 -0500 [thread overview]
Message-ID: <54D983B9.800@akamai.com> (raw)
In-Reply-To: <20150209215045.GU21418@twins.programming.kicks-ass.net>
On 02/09/2015 04:50 PM, Peter Zijlstra wrote:
> On Mon, Feb 09, 2015 at 08:05:57PM +0000, Jason Baron wrote:
>> diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
>> index 852143a..17d1039 100644
>> --- a/kernel/sched/wait.c
>> +++ b/kernel/sched/wait.c
>> @@ -71,8 +71,11 @@ static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
>> unsigned flags = curr->flags;
>>
>> if (curr->func(curr, mode, wake_flags, key) &&
>> - (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
>> + (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) {
>> + if (flags & WQ_FLAG_ROUND_ROBIN)
>> + list_move_tail(&curr->task_list, &q->task_list);
>> break;
>> + }
>> }
>> }
> I think you meant to write something like:
>
> if (curr->func(curr, mode, wake_flags, key) &&
> (flags & WQ_FLAG_EXCLUSIVE)) {
> if (flag & WQ_FLAG_ROUND_ROBIN)
> list_move_tail(&curr->task_list, &q->task_list);
> if (!--nr_exclusive)
> break;
> }
>
> Otherwise can only work for nr_exclusive==1.
Indeed. I'm also wondering if its worth avoiding the list_move_tail() for the case where nr_exclusive is initially 0. IE the wake all case, where we are just going to end up doing a bunch of list_move_tail() calls, but end up in the same state.
Thanks,
-Jason
next prev parent reply other threads:[~2015-02-10 4:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-09 20:05 [PATCH 0/2] Add epoll round robin wakeup mode Jason Baron
2015-02-09 20:05 ` [PATCH 1/2] sched/wait: add " Jason Baron
2015-02-09 20:26 ` Michael Kerrisk
2015-02-09 21:50 ` Peter Zijlstra
2015-02-10 4:06 ` Jason Baron [this message]
2015-02-10 9:03 ` Peter Zijlstra
2015-02-10 15:59 ` Jason Baron
2015-02-10 16:11 ` Peter Zijlstra
2015-02-09 20:06 ` [PATCH 2/2] epoll: introduce EPOLLEXCLUSIVE and EPOLLROUNDROBIN Jason Baron
2015-02-09 20:18 ` Andy Lutomirski
2015-02-09 21:32 ` Jason Baron
2015-02-09 22:45 ` Andy Lutomirski
2015-02-10 3:59 ` Jason Baron
2015-02-10 4:49 ` Eric Wong
2015-02-10 19:16 ` Jason Baron
2015-02-10 19:32 ` Eric Wong
2015-02-09 20:27 ` Michael Kerrisk
2015-02-09 20:25 ` [PATCH 0/2] Add epoll round robin wakeup mode Michael Kerrisk
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