From: Andrew Morton <akpm@linux-foundation.org>
To: hev <r@hev.cc>
Cc: linux-fsdevel@vger.kernel.org, Al Viro <viro@ZenIV.linux.org.uk>,
Davide Libenzi <davidel@xmailserver.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Eric Wong <e@80x24.org>, Jason Baron <jbaron@akamai.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Roman Penyaev <rpenyaev@suse.de>,
Sridhar Samudrala <sridhar.samudrala@intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND v4] fs/epoll: Remove unnecessary wakeups of nested epoll that in ET mode
Date: Fri, 27 Sep 2019 19:29:15 -0700 [thread overview]
Message-ID: <20190927192915.6ec24ad706258de99470a96e@linux-foundation.org> (raw)
In-Reply-To: <20190925015603.10939-1-r@hev.cc>
On Wed, 25 Sep 2019 09:56:03 +0800 hev <r@hev.cc> wrote:
> From: Heiher <r@hev.cc>
>
> Take the case where we have:
>
> t0
> | (ew)
> e0
> | (et)
> e1
> | (lt)
> s0
>
> t0: thread 0
> e0: epoll fd 0
> e1: epoll fd 1
> s0: socket fd 0
> ew: epoll_wait
> et: edge-trigger
> lt: level-trigger
>
> We only need to wakeup nested epoll fds if something has been queued to the
> overflow list, since the ep_poll() traverses the rdllist during recursive poll
> and thus events on the overflow list may not be visible yet.
>
> Test code:
Look sane to me. Do you have any performance testing results which
show a benefit?
epoll maintainership isn't exactly a hive of activity nowadays :(
Roman, would you please have time to review this?
next prev parent reply other threads:[~2019-09-28 2:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 1:56 [PATCH RESEND v4] fs/epoll: Remove unnecessary wakeups of nested epoll that in ET mode hev
2019-09-28 2:29 ` Andrew Morton [this message]
2019-09-28 19:07 ` Roman Penyaev
2019-09-30 11:55 ` Roman Penyaev
2019-10-03 16:13 ` Jason Baron
2019-10-07 10:54 ` Roman Penyaev
2019-10-07 16:42 ` Jason Baron
2019-10-07 18:30 ` Roman Penyaev
2019-10-07 18:43 ` Jason Baron
2019-10-07 19:10 ` Roman Penyaev
2019-10-09 6:03 ` Heiher
2019-10-08 9:55 ` Roman Penyaev
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