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From: "Eric D. Mudama" <edmudama@mail.bounceswoosh.org>
To: Giuliano Pochini <pochini@denise.shiny.it>
Cc: "Eric D. Mudama" <edmudama@mail.bounceswoosh.org>,
	Tom Vier <tmv@comcast.net>,
	linux-kernel@vger.kernel.org
Subject: Re: Linux Kernel 2.6.6 IDE shutdown problems.
Date: Tue, 25 May 2004 11:02:14 -0600	[thread overview]
Message-ID: <20040525170214.GA26785@bounceswoosh.org> (raw)
In-Reply-To: <Pine.LNX.4.58.0405251101240.1197@denise.shiny.it>

On Tue, May 25 at 11:05, Giuliano Pochini wrote:
>
>
>On Mon, 24 May 2004, Eric D. Mudama wrote:
>
>> Picture a nice fast drive doing 100 writes/second to the media... if
>> you give it over 200 writes at a time, it'll occupy your 2 seconds.
>> Newer drives with 8MB or larger buffers are certainly capable of
>> caching a lot more than 200 writes...
>
>Quite unlikely. Usually disks have a big cache but it can hold a very
>limited number of blocks. 8MB of cache is probably divided in 8 blocks
>of 1MB each.

Sorry, but that isn't true, unless some company is just plain stupid.

Everyone has different metrics for cache granularity based on their
cache architecture, but I can assure you that 8x 1MB segments is off
by 1-2 orders of magnitude, and has been for years.

In practice, depending on the workload, there may appear to only be 8
active segments as drives today can merge cache segments or other
similar things (architectually dependant), but the worst-case (best
case?) is significantly more.

--eric



-- 
Eric D. Mudama
edmudama@mail.bounceswoosh.org


  parent reply	other threads:[~2004-05-25 17:02 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-05-15 12:20 Justin Piszcz
2004-05-15 13:06 ` Bartlomiej Zolnierkiewicz
2004-05-17 22:25   ` Bill Davidsen
2004-05-24  2:41     ` Tom Vier
2004-05-24  3:09       ` Daniel Pittman
2004-05-24 17:16       ` Eric D. Mudama
2004-05-25  9:05         ` Giuliano Pochini
2004-05-25 15:03           ` Bartlomiej Zolnierkiewicz
2004-05-26 10:21             ` Ian Stirling
2004-05-25 17:02           ` Eric D. Mudama [this message]
  -- strict thread matches above, loose matches on Subject: below --
2004-05-15 14:59 Justin Piszcz
2004-05-15 12:02 Justin Piszcz

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