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 17:29:30 +0800 [thread overview]
Message-ID: <1196674170.25646.121.camel@ymzhang> (raw)
In-Reply-To: <20071130100845.GB2201@elte.hu>
On Fri, 2007-11-30 at 11:08 +0100, 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:
>
> http://download.fedora.redhat.com/pub/fedora/linux/development/source/SRPMS/java-1.7.0-icedtea-1.7.0.0-0.20.b23.snapshot.fc9.src.rpm
I used BEA Jrockit to run volanoMark. Because of no Jrockit source codes, so
I retested volanoMark by jre-1.7.0-icedtea.x86_64 java of Fedora Core 8 on my stoakley (8-core)
machine with kernel 2.6.24-rc3.
1) Jrockit: sched_compat_yield=0's result is less than 15% of sched_compat_yield=1's.
2) jre-1.7.0-icedtea: sched_compat_yield=0's result is less than 89% of sched_compat_yield=1's.
So JVM really has much impact on the regression.
I checked the source codes of openjdk and found Thread.yield is implemented as native sched_yield.
If java applications call Thread.yield, it just calls sched_yield. garbage collection and other JVM
threads also calls Thread.yield. That's why 2 different JVM have different regression percentage.
Although no source codes of volanoMark, I suspect it calls Thread.sched. volanoMark is a kind
of chatroom benchmark. When a client sends out a message, server will send the message to all clients.
I suspect the client calls Thread.yield after sending out a couple of messages.
2 JVM all have regression if sched_compat_yield=0.
I ran some testing, such like iozone/specjbb/tbench/dbench/sysbench, and didn't see regression.
-yanmin
next prev parent reply other threads:[~2007-12-03 9:30 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
2007-12-03 10:17 ` Ingo Molnar
2007-12-03 9:29 ` Zhang, Yanmin [this message]
2007-12-03 10:05 ` Ingo Molnar
2007-12-04 6:40 ` Zhang, Yanmin
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