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Date: Thu, 30 Dec 2004 20:56:45 +0200
From: "Eli Zaretskii" <eliz AT gnu DOT org>
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In-reply-to: <qip7t0pp2a6lbcndsjs9m1g4tv2ekfas5m@4ax.com> (message from Brian
	Inglis on Thu, 30 Dec 2004 11:32:27 GMT)
Subject: Re: DREADED fseek
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> From: Brian Inglis <Brian DOT Inglis AT SystematicSW DOT Invalid>
> Date: Thu, 30 Dec 2004 11:32:27 GMT
> 
> >> Saw that: looks like it just flushes buffered writes, not all buffered
> >> data read. 
> >
> >On what OS?
> 
> In flushdc.{c,txh} and RBIL. 
> None of them say that the list of all cached blocks is cleared,

Yes, but did you actually try that, or did you only look at the
sources?  If you did try it and it didn't remove the read data, please
tell on what OS was that.

Note that the system call used by the function not only flushes the
cache, but also resets the disk drive, which should do what you want
(and at least on plain DOS, it actually did).

> or that caching is disabled.

The function doesn't disable caching, but if you invoke it after every
test, you should see the behavior of uncached data, i.e. raw disk I/O
performance.  Isn't that what you wanted?