[Beowulf] Feedback on large pages in Linux

Vincent Diepeveen diep at xs4all.nl
Sat Jul 22 22:31:00 EDT 2006


----- Original Message ----- 
From: "Greg Lindahl" <greg.lindahl at qlogic.com>
To: <beowulf at beowulf.org>
Sent: Sunday, July 23, 2006 12:19 AM
Subject: Re: [Beowulf] Feedback on large pages in Linux


> On Fri, Jul 21, 2006 at 11:39:23PM -0400, hahn at physics.mcmaster.ca wrote:
>
>> it would be incredibly useful if the HPC community could come up with
>> some actual numbers on how important bigpages are.  I'm ashamed to say
>> that I haven't made any effort to measure this on any of my clusters.
>> oprofile appears to make it pretty easy to capture real data on how
>> often TLB's are a problem.
>
> Actually it's not hard to measure the benefit -- take an OS like
> Solaris and use Sun's SpecOMP runs with and without huge pages...
> also spec_rate...  insomuch as you ever see their SunStudio compilers
> beating ours, huge pages are involved. But I've never seen a study
> break out the benefits separately, they're always Linux & small pages
> & compiler A vs. not Linux & large pages & compiler B...
>
> -- greg

Actually in search it's a few % when enabling it in the kernel and using 
huge
hashtable. 100% similar conditions.

Vincent

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