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Subject: Re: sched_yield: delete sysctl_sched_compat_yield
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>
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Date: Tue, 04 Dec 2007 14:40:13 +0800
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On Mon, 2007-12-03 at 11:05 +0100, Ingo Molnar wrote:
> * Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:
> 
> > 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.
> 
> yeah, so far only volanomark seems to be affected by this, and if it 
> indeed calls Thread.yield artificially it's a pretty stupid benchmark 
> and it's not the fault of the JDK. If we had the source to volanomark we 
> could fix this easily.
> 
> > 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.
> 
> which JVM was utilized by the specjbb (Java Business Benchmark) tests?
BEA Jrockit. It supports huge pages which promote performance for about 8%~10%.

-yanmin