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Date: Mon, 12 Nov 2001 16:02:30 -0800
From: Mingming cao <cmm@us.ibm.com>
Organization: Linux Technology Center
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To: Linus Torvalds <torvalds@transmeta.com>
CC: Alan Cox <alan@lxorguk.ukuu.org.uk>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        lse-tech@lists.sourceforge.net
Subject: Re: [PATCH]Disk IO statistics for all disks
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Linus Torvalds wrote:
> 
> On Mon, 12 Nov 2001, Mingming cao wrote:
> >
> > This is a patch to dynamically allocate the data buffers for the disk
> > statistics, and to extend the gathering of disk statistics to include
> > major numbers greater than 15.
> 
> I would suggest instead just moving the statistics into the request queue,
> at which point it should be nicely per-controller already, and quite
> independent of major numbers etc.
> 
> Oh, and it will be faster too, because you only need one lookup.
> 
>                 Linus
I saw your suggestions related to this about a year ago.  I like the
idea of doing statistics per-controller and getting rid of disk_index().
But by moving statistics into the request queue, under the current
implementation, we have to allocate statistics memory for every major,
since for every major there is a request_queue asscoiated with
it(blk_dev[MAX_BLKDEV]).  Do you care about this?  

-- 
Mingming Cao
IBM Linux Technology Center
503-578-5024  IBM T/L: 775-5024
cmm@us.ibm.com
http://www.ibm.com/linux/ltc
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