From: Oliver Neukum <oliver@neukum.org>
To: "Morales, Alejandra" <alejandra.morales@tum.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Doubts on IO requests in USB subsystem
Date: Mon, 16 Sep 2013 13:06:39 +0200 [thread overview]
Message-ID: <1379329599.15916.25.camel@linux-fkkt.site> (raw)
In-Reply-To: <9E3F9C2076C45D4783F09B90D5BE77CE18E667@BADWLRZ-SWMBX13.ads.mwn.de>
On Mon, 2013-09-16 at 10:33 +0000, Morales, Alejandra wrote:
> 2013/9/9 Oliver Neukum <oliver@neukum.org>
> >
> > Your prime suspect is the detection of medium change which was
> > moved into the kernel in 3.2 or so. It can be disabled by sysfs.
> > Generally the notion that a certain task originates a read or write
> > on a block device is iffy. Read-ahead and shared data structures
> > make it impossible to accurately tell.
> >
> > USB storage devices are notorious for setting the removable bit
> > even if they have no removable medium.
> >
>
> Thanks for the answer Oliver. Unfortunately it doesn't seem to be the
> medium change detection what is causing these requests, since the
> removable bit is disabled and the polling period is set to -1:
Interesting. Then you have no choice. Make a usbmon trace and look
at the SCSI commands going to the device.
HTH
Oliver
next prev parent reply other threads:[~2013-09-16 11:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-09 8:20 Doubts on IO requests in USB subsystem Morales, Alejandra
2013-09-09 16:40 ` Oliver Neukum
2013-09-16 10:33 ` Morales, Alejandra
2013-09-16 11:06 ` Oliver Neukum [this message]
2013-11-06 11:51 ` Morales, Alejandra
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