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Date: Mon, 10 Feb 2003 13:39:54 +0300
From: Hans Reiser <reiser@namesys.com>
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To: Andrew Morton <akpm@digeo.com>
CC: andrea@suse.de, piggin@cyberone.com.au, jakob@unthought.net,
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Subject: Re: stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3
 / aa / rmap with contest]
References: <Pine.LNX.4.50L.0302100211570.12742-100000@imladris.surriel.com>	<Pine.LNX.4.44.0302092018180.15944-100000@dlang.diginsite.com>	<20030209203343.06608eb3.akpm@digeo.com>	<20030210045107.GD1109@unthought.net>	<3E473172.3060407@cyberone.com.au>	<20030210073614.GJ31401@dualathlon.random>	<3E47579A.4000700@cyberone.com.au>	<20030210080858.GM31401@dualathlon.random>	<20030210001921.3a0a5247.akpm@digeo.com>	<3E477802.8070008@namesys.com> <20030210020602.0ff7d3f5.akpm@digeo.com>
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Andrew Morton wrote:

>Hans Reiser <reiser@namesys.com> wrote:
>  
>
>>reiser4 does directory readahead.  It gets a lot of gain from it. 
>>    
>>
>
>What is "a lot"?
>
>
>  
>
Vladimir Saveliev had the numbers ready at hand after all, and said:

The most noticeable gain is found in the folowing test (not sure that it 
can be considered as effective readahead though): ls -l over directory 
containing 30000 files (named numerically) created in random order :
4.87 with no readahead
2.99 with readahead (which is limited by 25% of ram or by directory and 
all its stat data)

-- 
Hans


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