From: James Bottomley <James.Bottomley-l3A5Bk7waGM@public.gmane.org>
To: Ramya Desai <ramya.desai-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: USB list <linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Greg KH <greg-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>,
Alan Stern
<stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>
Subject: Re: Maximum data size in a single transfer for MS driver
Date: Wed, 17 Feb 2010 09:02:32 -0600 [thread overview]
Message-ID: <1266418952.2787.5.camel@mulgrave.site> (raw)
In-Reply-To: <3e7aae31002170437i52ba4ba1w10c1ff224d9b37ef-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Wed, 2010-02-17 at 18:07 +0530, Ramya Desai wrote:
> What is the number of maximum sectors that SCSI can send to MS driver
> in a single data transfer?
I have no idea what the MS driver is, so it's impossible to answer
specifically. Generically, for drivers that expect a contiguous sg
list, then 128 elements (512k) is the maximum. For drivers updated to
use the sg chaining API (which is at least all of those in
drivers/scsi), there is no maximum except what the hardware is limited
to.
> I changed the max_sectors in struct scsi_host_template
> usb_stor_host_template structure to 2048. Still, SCSI is sending 1024
> sectors (512 KB) in a single data transfer.
> I know that my device supports 1 MB data in a sigle transfer. How can
> I change this to 1 MB?
As long as the driver supports chaining, you increase it
in /sys/block/dev>/queue/max_sectors_kb. For compatibility reasons this
stays clamped at 512 unless a user specifically raises it.
James
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next prev parent reply other threads:[~2010-02-17 15:02 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-17 12:37 Maximum data size in a single transfer for MS driver Ramya Desai
[not found] ` <3e7aae31002170437i52ba4ba1w10c1ff224d9b37ef-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-02-17 15:02 ` James Bottomley [this message]
2010-02-18 8:46 ` Ramya Desai
2010-02-18 15:47 ` James Bottomley
[not found] ` <1266508049.4355.37.camel-0iu6Cu4xQGLYCGPCin2YbQ@public.gmane.org>
2010-02-18 16:24 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1002181115120.1294-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2010-02-18 16:30 ` James Bottomley
[not found] ` <1266510627.4355.41.camel-0iu6Cu4xQGLYCGPCin2YbQ@public.gmane.org>
2010-02-18 16:51 ` Alan Stern
2010-02-19 12:43 ` Ramya Desai
2010-02-19 14:26 ` James Bottomley
2010-02-22 12:50 ` Ramya Desai
[not found] ` <3e7aae31002220450o6f83d2f3n45c795d70ef01f72-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-02-22 13:06 ` James Bottomley
2010-02-22 14:15 ` Ramya Desai
2010-02-22 17:44 ` Alan Stern
2010-02-22 18:07 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1002221232160.1251-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2010-02-23 15:29 ` Ramya Desai
2010-02-23 16:49 ` Alan Stern
2010-02-23 17:00 ` Martin K. Petersen
2010-02-23 18:01 ` Alan Stern
[not found] ` <Pine.LNX.4.44L0.1002231253320.1308-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2010-02-24 13:07 ` Ramya Desai
2010-02-24 13:12 ` Jens Axboe
2010-02-24 16:30 ` Alan Stern
2010-02-24 19:07 ` Jens Axboe
2010-02-25 14:47 ` Ramya Desai
2010-02-25 14:44 ` Ramya Desai
2010-02-25 16:37 ` Alan Stern
2010-02-25 16:49 ` Martin K. Petersen
2010-02-25 16:53 ` Martin K. Petersen
2010-02-25 17:54 ` Jens Axboe
[not found] ` <yq1zl2xl0j3.fsf-+q57XtR/GgMb6DWv4sQWN6xOck334EZe@public.gmane.org>
2010-02-25 18:28 ` Alan Stern
2010-02-25 19:05 ` Martin K. Petersen
[not found] ` <yq1iq9lkueh.fsf-+q57XtR/GgMb6DWv4sQWN6xOck334EZe@public.gmane.org>
2010-02-25 19:47 ` Alan Stern
2010-02-26 3:37 ` Martin K. Petersen
[not found] ` <Pine.LNX.4.44L0.1002251132170.1686-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
2010-02-25 17:52 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2010-02-25 16:59 scameron
2010-02-25 17:00 ` scameron
2010-02-25 17:18 ` scameron
2010-02-25 17:28 ` Martin K. Petersen
2010-02-25 17:41 ` Boaz Harrosh
2010-02-25 17:58 ` Martin K. Petersen
2010-02-25 19:07 ` Martin K. Petersen
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