linux-kernel - Re: [PATCH 2/3] x86: Implement prctl PR_GET_TSC and PR_SET

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Date:	Sun, 13 Apr 2008 15:02:45 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Erik Bosman <ejbosman@...vu.nl>
CC:	Arjan van de Ven <arjan@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Andrea Arcangeli <andrea@...share.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] x86: Implement prctl PR_GET_TSC and PR_SET_TSC

Erik Bosman wrote:
> 
> It took me a while, but I have done some tests om my system with and
> without my patch applied.
> 
> All deamons but klogd/syslogd were shut down andI used the following
> command:
> 
> LMBENCH_SCHED="SINGLE" \
> /usr/lib/lmbench/bin/{i686-pc,x86_64}-linux-gnu/lat_ctx -s 0 2
> 
> The variation was quite high so I ran it a 1000 times for each
> configuration.
> 
> x86_32, patch applied,     1000x repeated, avg: 1.319, rmse: 0.081
> x86_32, patch not applied, 1000x repeated, avg: 1.335, rmse: 0.107
> 
> x86_64, patch applied,     1000x repeated, avg: 1.417, rmse: 0.0716
> x86_64, patch not applied, 1000x repeated, avg: 1.423, rmse: 0.0745
> 
> This is on a core 2 duo E6300.
> 

OK, so it sounds like there is no measurable difference.  Good.

	-hpa
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