From: Linus Torvalds <torvalds@linux-foundation.org>
To: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Ratan Nalumasu <rnalumasu@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] do_wait wakeup optimization
Date: Wed, 19 Nov 2008 19:35:45 -0800 (PST) [thread overview]
Message-ID: <alpine.LFD.2.00.0811191929450.21698@nehalem.linux-foundation.org> (raw)
In-Reply-To: <20081120012017.3CC3C15423A@magilla.localdomain>
On Wed, 19 Nov 2008, Roland McGrath wrote:
>
> Ratan Nalumasu reported that in a process with many threads doing
> different, mutually-exclusive waitpid() calls, there were a lot of
> unnecessary wakeups. Every waiting thread in the process wakes up to
> loop through the children and see that the only ones it cares about
> are still not ready.
Patch looks sane, and look worth queueing up for the next merge window.
But if somebody actually has numbers and/or can talk about the real-life
load that made people even notice this, that would be good to add to the
description.
Also, do we really need to call eligible_child() twice? The real wait only
does it once in that "wait_consider_task()". Explanations would be good..
Linus
next prev parent reply other threads:[~2008-11-20 3:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <93ad5f3f0808181334i684e68b7yb61e3586d35880f6@mail.gmail.com>
[not found] ` <20080819005439.GA14821@elte.hu>
[not found] ` <93ad5f3f0808181804m3b74fe68v1fdcf4edf6c7b465@mail.gmail.com>
2008-08-19 1:35 ` Patch for improving wait performance with NPTL Roland McGrath
[not found] ` <20080819214546.9BD5715426B@magilla.localdomain>
[not found] ` <93ad5f3f0808191746g44acbccdm715222698ed20ee1@mail.gmail.com>
[not found] ` <20080820010415.EB87B15449D@magilla.localdomain>
[not found] ` <93ad5f3f0808191851i1fdd0332g8befbc538551f24@mail.gmail.com>
[not found] ` <93ad5f3f0808221333pe9b95fp886f6313b4be384e@mail.gmail.com>
[not found] ` <20080823013655.F3B3615426C@magilla.localdomain>
[not found] ` <93ad5f3f0808261601g4fa6429dgbcb21e4218e92f2a@mail.gmail.com>
[not found] ` <20080826230620.5865E154233@magilla.localdomain>
[not found] ` <93ad5f3f0811191404g28361b1ei329c3e326b21087d@mail.gmail.com>
2008-11-20 1:20 ` [PATCH] do_wait wakeup optimization Roland McGrath
2008-11-20 3:35 ` Linus Torvalds [this message]
2008-11-20 3:59 ` Roland McGrath
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