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Subject: RE: [PATCH] lock stat for -rt 2.6.20-rc2-rt2.2.lock_stat.patch
Date: Wed, 3 Jan 2007 16:25:46 -0800
Message-ID: <9D2C22909C6E774EBFB8B5583AE5291C01A4FB7D@fmsmsx414.amr.corp.intel.com>
In-Reply-To: <20070104001225.GA31434@gnuppy.monkey.org>
Thread-Topic: [PATCH] lock stat for -rt 2.6.20-rc2-rt2.2.lock_stat.patch
Thread-Index: AccvlQtznhyyAOpAS0KJGWyZ7ftWhgAAJmmw
From: "Chen, Tim C" <tim.c.chen@intel.com>
To: "Bill Huey \(hui\)" <billh@gnuppy.monkey.org>
Cc: "Ingo Molnar" <mingo@elte.hu>, <linux-kernel@vger.kernel.org>,
       "Siddha, Suresh B" <suresh.b.siddha@intel.com>,
       "Peter Zijlstra" <a.p.zijlstra@chello.nl>,
       "Steven Rostedt" <rostedt@goodmis.org>,
       "Thomas Gleixner" <tglx@linutronix.de>,
       "Daniel Walker" <dwalker@mvista.com>
Sender: linux-kernel-owner@vger.kernel.org
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Lines: 21

Bill Huey (hui) wrote:
> 
> Good to know that. What did the output reveal ?
> 
> What's your intended use again summarized ? futex contention ? I'll
> read the first posting again.
> 

Earlier I used latency_trace and figured that there was read contention
on mm->mmap_sem during call to _rt_down_read by java threads
when I was running volanomark.  That caused the slowdown of the rt
kernel
compared to non-rt kernel.  The output from lock_stat confirm
that mm->map_sem was indeed the most heavily contended lock.

Tim
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