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Reply-To: <frey@scs.ch>
From: "Martin Frey" <frey@scs.ch>
To: "'Jens Axboe'" <axboe@suse.de>, "'Shailabh Nagar'" <nagar@us.ibm.com>
Cc: "'Reto Baettig'" <baettig@scs.ch>, <lse-tech@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>
Subject: RE: [Lse-tech] Re: Preliminary results of using multiblock raw I/O
Date: Tue, 23 Oct 2001 05:59:03 -0400
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>I haven't seen the SGI rawio patch, but I'm assuming it used kiobufs to
>pass a single unit of 1 meg down at the time. Yes currently we do incur
>significant overhead compared to that approach.
>
Yes, it used kiobufs to get a gatherlist, setup a gather DMA out
of that list and submitted it to the SCSI layer. Depending on
the controller 1 MB could be transfered with 0 memcopies, 1 DMA,
1 interrupt. 200 MB/s with 10% CPU load was really impressive.

Regards, Martin
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