Message-ID: <454799D8.1060908@cfl.rr.com>
Date: Tue, 31 Oct 2006 13:45:44 -0500
From: Phillip Susi <psusi@cfl.rr.com>
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To: Olivier Galibert <galibert@pobox.com>,
       "Hack inc." <linux-kernel@vger.kernel.org>
Subject: Re: Reading a bunch of file as fast a possible
References: <20061031172258.GB8230@dspnet.fr.eu.org>
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Yes, it sounds like you are looking for aio, possibly with O_DIRECT if 
you would prefer that the reads not churn the cache.

Olivier Galibert wrote:
> After searching for kinda-keywords in a locked-in-memory index, I get
> a list of 50-100 files out of several hundred thousands I want to read
> as fast as possible.  I can ensure that the directory structure in hot
> in the dcache by re-reading it from time to time, but there isn't
> enough memory to lock the documents there.  So I'd like to read 50-100
> files for which I have the sizes (I put them in the index) and memory
> space as fast as possible (less than 0.1s would be great) from
> cold-ish cache.
> 
> The best way is I think to find a way to give all the requests to the
> system and have it sort them optimally at the elevator level.  But how
> can I do that?  Can aio do it, or something else?
> 
>   OG.

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