From: "Alex,Shi" <alex.shi@intel.com>
To: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@elte.hu" <mingo@elte.hu>,
"Chen, Tim C" <tim.c.chen@intel.com>,
"Li, Shaohua" <shaohua.li@intel.com>
Subject: Re: [PATCH] sched: recover sched_yield task running time increase
Date: Thu, 07 Apr 2011 14:43:16 +0800 [thread overview]
Message-ID: <1302158596.15889.7499.camel@debian> (raw)
In-Reply-To: <4D9D55EF.3090606@redhat.com>
On Thu, 2011-04-07 at 14:13 +0800, Rik van Riel wrote:
> On 04/06/2011 11:08 PM, Alex,Shi wrote:
> > On Wed, 2011-04-06 at 16:04 +0800, Peter Zijlstra wrote:
> >> On Wed, 2011-04-06 at 06:33 +0800, Alex Shi wrote:
>
> >> You do know that any app that relies on sched_yield behaviour is more
> >> than broken? Using sched_yield() for anything other than SCHED_FIFO
> >> tasks is well outside spec.
> >>
> >> Furthermore, apparently you used sysctl_sched_compat_yield, which was
> >> bound to disappear some time, since with the default settings the yield
> >> semantics didn't actually change.
> >
> > Yes, I used sched_compat_yield, otherwise volano will become extremely
> > slow in my single machine testing. We may reconsider our testing
> > setting.
>
> With what JVM is this happening?
I used openjdk from fedora 10~13 and jrockit-R27.3.1-jre1.5.0_11, both
of them use sched_yield much. And I just did a quick try with
jrockit-R27.4.0-jre1.6.0_02.x86_64, it had same problem.
>
> Surely not every JVM uses user space spinlocks and
> yield, when we have futexes available?
No, just 7 times futex called in testing, so I think the JVM did not use
it.
>
>
>
next prev parent reply other threads:[~2011-04-07 6:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-05 22:33 [PATCH] sched: recover sched_yield task running time increase Alex Shi
2011-04-06 5:07 ` Rik van Riel
2011-04-06 6:15 ` Alex,Shi
2011-04-06 7:01 ` Mike Galbraith
2011-04-06 13:28 ` Shi, Alex
2011-04-07 2:44 ` Mike Galbraith
2011-04-06 8:04 ` Peter Zijlstra
2011-04-06 14:42 ` Rik van Riel
2011-04-06 15:25 ` Peter Zijlstra
2011-04-07 3:08 ` Alex,Shi
2011-04-07 6:13 ` Rik van Riel
2011-04-07 6:43 ` Alex,Shi [this message]
2011-04-07 8:52 ` Ingo Molnar
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