From: Eric Wong <normalperson@yhbt.net>
To: Jason Baron <jbaron@akamai.com>
Cc: lsf-pc@lists.linux-foundation.org,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
famz@redhat.com
Subject: Re: [LSF/MM TOPIC] epoll topics
Date: Mon, 19 Jan 2015 03:50:48 +0000 [thread overview]
Message-ID: <20150119035048.GA4533@dcvr.yhbt.net> (raw)
In-Reply-To: <54B88EC5.9020904@akamai.com>
Jason Baron <jbaron@akamai.com> wrote:
> In addition, Eric Wong has proposed a scheme using 'wait free queues' to
> improve lock contention between wakeups and event gathering:
> https://lkml.org/lkml/2013/3/14/14.
Thanks for bringing this up again. wfcqueue for epoll is still on hold
until I take care of other problems in userspace. I'd welcome other
interested folks to help get it into shape again.
> In addition, we've observed some short comings from our production systems.
> Because wait queues are woken up in order, we can get unfair loading
> across threads,
Are you referring to LIFO scheduling of epoll_wait calling
__add_wait_queue_exclusive? I always thought LIFO was preferable
since it kept the same threads active to reduce cache misses.
> and we can also receive unecessary wakeups. It would be
> great to discuss these topics further.
I'm happy to discuss via email; but I don't travel well.
next prev parent reply other threads:[~2015-01-19 3:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-16 4:08 [LSF/MM TOPIC] epoll topics Jason Baron
2015-01-19 3:50 ` Eric Wong [this message]
2015-01-20 18:55 ` Jason Baron
2015-01-20 19:58 ` Eric Wong
2015-01-20 20:37 ` Jason Baron
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