From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
Arjan van de Ven <arjan@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: sched_yield: delete sysctl_sched_compat_yield
Date: Mon, 03 Dec 2007 17:41:09 +0800 [thread overview]
Message-ID: <1196674869.25646.142.camel@ymzhang> (raw)
In-Reply-To: <20071203084557.GA13156@elte.hu>
On Mon, 2007-12-03 at 09:45 +0100, Ingo Molnar wrote:
> * Nick Piggin <nickpiggin@yahoo.com.au> wrote:
>
> > On Friday 30 November 2007 21:08, Ingo Molnar wrote:
> > > * Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> > > > Haven't we been asking JVMs to use futexes or posix locking for years
> > > > and years now? [...]
> > >
> > > i'm curious, with what JVM was it tested and where's the source so i
> > > can fix their locking for them? Can the problem be reproduced with:
> >
> > Sure, but why shouldn't the compat behaviour be the default, and the
> > sysctl go away?
> >
> > It makes older JVMs work better, it is slightly closer to the old
> > behaviour, and it is arguably a less surprising result.
>
> as far as desktop apps such as firefox goes, the exact opposite is true.
> We had two choices basically: either a "more agressive" yield than
> before or a "less agressive" yield. Desktop apps were reported to hurt
> from a "more agressive" yield (firefox for example gets some pretty bad
> delays),
Why not to change source codes of firefox? If the sched_compat_yield=0,
the sys_sched_yield almost does nothing but returns, so firefox could just
do not call sched_yield. I assume 'sched_compat_yield=0' ~ no_call_to_sched_yield.
It's easier to delete calls to sched_yield in applications than to tune
calls to sched_yield.
> so we defaulted to the less agressive method. (and we defaulted
> to that in v2.6.23 already) Really, in this sense volanomark is another
> test like dbench - we care about it but not unconditionally and in this
> case it's a really silly API use that is at the center of the problem.
> Talking about the default alone will not bring us forward, but we can
> certainly add helpers to identify SCHED_OTHER::yield tasks - a once per
> bootup warning perhaps?
>
> Ingo
next prev parent reply other threads:[~2007-12-03 9:42 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-27 9:33 sched_yield: delete sysctl_sched_compat_yield Zhang, Yanmin
2007-11-27 11:17 ` Ingo Molnar
2007-11-27 22:57 ` Arjan van de Ven
2007-11-30 2:46 ` Nick Piggin
2007-11-30 2:51 ` Arjan van de Ven
2007-11-30 3:02 ` Nick Piggin
2007-11-30 3:15 ` Zhang, Yanmin
2007-11-30 3:29 ` Nick Piggin
2007-11-30 4:32 ` Zhang, Yanmin
2007-11-30 10:08 ` Ingo Molnar
2007-12-03 4:27 ` Nick Piggin
2007-12-03 8:45 ` Ingo Molnar
2007-12-03 9:17 ` Nick Piggin
2007-12-03 9:35 ` Zhang, Yanmin
2007-12-03 9:57 ` Ingo Molnar
2007-12-03 10:15 ` Nick Piggin
2007-12-03 10:33 ` Ingo Molnar
2007-12-03 11:02 ` Nick Piggin
2007-12-03 11:37 ` Ingo Molnar
2007-12-03 17:04 ` David Schwartz
2007-12-03 17:37 ` Chris Friesen
2007-12-03 19:12 ` David Schwartz
2007-12-03 19:56 ` Chris Friesen
2007-12-03 21:39 ` Mark Lord
2007-12-03 21:48 ` Ingo Molnar
2007-12-03 21:57 ` Mark Lord
2007-12-03 22:05 ` Ingo Molnar
2007-12-03 22:18 ` Mark Lord
2007-12-03 22:33 ` Ingo Molnar
2007-12-04 0:18 ` Nick Piggin
2007-12-04 0:30 ` David Schwartz
2007-12-04 2:09 ` Nick Piggin
2007-12-04 1:02 ` Nick Piggin
2007-12-03 9:41 ` Zhang, Yanmin [this message]
2007-12-03 10:17 ` Ingo Molnar
2007-12-03 9:29 ` Zhang, Yanmin
2007-12-03 10:05 ` Ingo Molnar
2007-12-04 6:40 ` Zhang, Yanmin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1196674869.25646.142.camel@ymzhang \
--to=yanmin_zhang@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=arjan@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=nickpiggin@yahoo.com.au \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).