Subject: Re: [Fwd: [Linux-usb-users] Re: 2.4.0-test11-pre7 -- The USB ORB Drive works vastly better when the media is formatted with FAT32.]
To: miles@speakeasy.org (Miles Lane)
Date: Sun, 19 Nov 2000 13:01:42 +0000 (GMT)
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <3A1797A5.4060003@speakeasy.org> from "Miles Lane" at Nov 19, 2000 01:04:37 AM
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Message-Id: <E13xU6K-0002iK-00@the-village.bc.nu>
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Sender: linux-kernel-owner@vger.kernel.org

>  > > protocol for USB communication being diluted down.  Realize that a 1KB
>  > > block has 4 times the overhead of a 4KB block (on a per-byte-of-data
>  > > basis).  The usb-storage driver attempts to get the SCSI layer to give it

That guess would be dubious. Its also not IMHO enough to explain the
speed difference. That looks like something is causing far bigger delays
internally.

>  > > the largest requests possible, but that layer is limited by what the
>  > > filesystem layer is willing to give.

Providing your driver supports scatter gather you will get large chunks handed
down to the driver. In the scsi world you can control that with the
scsi host template settings. (both the scatter/gather limit and whether you
want the scsi layer to try and merge requests for you)

Alan

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