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From: Ed Tomlinson <tomlins@cam.org>
Organization: me
To: Rik Van Riel <riel@redhat.com>
Subject: Re: [PATCH] 0/2 swap token tuning
Date: Mon, 27 Jun 2005 19:46:32 -0400
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       Song Jiang <sjiang@lanl.gov>
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On Sunday 26 June 2005 18:34, Rik Van Riel wrote:
> A while ago the swap token (aka token based thrashing control)
> mechanism was introduced into Linux.  This code improves performance
> under heavy VM loads, but can reduce performance under very light
> VM loads.
> 
> The cause turns out to be me overlooking something in the original
> token based thrashing control paper: the swap token is only supposed
> to be enforced while the task holding the swap token is paging data
> in, not while the task is running (and referencing its working set).
> 
> The temporary solution in Linux was to disable the swap token code
> and have users turn it on again via /proc.  The following patch
> instead approximates the "only enforce the swap token if the task
> holding it is swapping something in" idea.  This should make sure
> the swap token is effectively disabled when the VM load is low.
> 
> I have not benchmarked these patches yet; instead, I'm posting
> them before the weekend is over, hoping to catch a bit of test
> time from others while my own tests are being run ;)

Rik,

What are the suggested  values to put into /proc/sys/vm/swap_token_timeout ?
The docs are not at all clear about this (proc/filesystems.txt).

TIA,
Ed Tomlinson