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From: Martin Dalecki <dalecki@evision-ventures.com>
To: Roy Sigurd Karlsbakk <roy@karlsbakk.net>
Cc: Rik van Riel <riel@conectiva.com.br>,
	Marcelo Tosatti <marcelo@conectiva.com.br>,
	linux-kernel@vger.kernel.org
Subject: Re: /proc/sys/vm/(max|min)-readahead effect????
Date: Thu, 06 Dec 2001 11:09:27 +0100	[thread overview]
Message-ID: <3C0F43D7.87B3948@evision-ventures.com> (raw)
In-Reply-To: <Pine.LNX.4.30.0112051924560.3073-100000@mustard.heime.net>

Roy Sigurd Karlsbakk wrote:
> 
> > I suspect the per-device readahead for IDE is limiting the
> > effect of vm_max_readahead ...
> 
> hm...
> 
> any way to avoid this? I mean... The readahead in vm is layered above the
> actual device, and should therefore not be limited... Am I right? You
> could do several device calls, and fake readahead, and probably get pretty
> much out of it.

He means the hardware device read ahead, which can be changed by using
hdparm -a 32 -A1 /dev/hda
for example.
The value of the read ahead one layer on top of it
(read_ahead array) can't have *any* impact on performance.

  reply	other threads:[~2001-12-06 10:20 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-12-05 16:21 /proc/sys/vm/(max|min)-readahead effect???? Roy Sigurd Karlsbakk
2001-12-05 16:51 ` Marcelo Tosatti
2001-12-05 18:09   ` Roy Sigurd Karlsbakk
2001-12-05 16:58     ` Marcelo Tosatti
2001-12-05 18:20       ` Roy Sigurd Karlsbakk
2001-12-05 19:43         ` James Stevenson
2001-12-05 20:06           ` Roy Sigurd Karlsbakk
2001-12-05 20:53             ` James Stevenson
2001-12-06 11:45               ` Roy Sigurd Karlsbakk
2001-12-06 18:44               ` Bernd Eckenfels
2001-12-05 18:22   ` Rik van Riel
2001-12-05 18:27     ` Roy Sigurd Karlsbakk
2001-12-06 10:09       ` Martin Dalecki [this message]
2001-12-05 20:13 ` Andrew Morton
2001-12-05 20:53   ` Roger Larsson
2001-12-06 11:31   ` Roy Sigurd Karlsbakk
2001-12-06 18:46     ` Bernd Eckenfels
2001-12-07 11:25       ` Roy Sigurd Karlsbakk

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