RE: Drivers: scsi

[KY Srinivasan <kys@microsoft.com>]

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> -----Original Message-----
> From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com]
> Sent: Wednesday, October 24, 2012 6:25 PM
> To: KY Srinivasan
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; ohering@suse.com; hch@infradead.org; linux-
> scsi@vger.kernel.org
> Subject: Re: Drivers: scsi
> 
> On Wed, 2012-10-24 at 09:25 -0700, K. Y. Srinivasan wrote:
> > When the low level driver returns SCSI_MLQUEUE_DEVICE_BUSY,
> > how is the command retried; I suspect the retry is done after some delay.
> 
> Delay depends mainly on I/O pressure and the unplug timer in the block
> layer.
> 
> > Is this delay programmable? If the device state changes,
> > can the low level driver notify upper layers that it can now handle
> > the command that it had failed earlier with SCSI_MLQUEUE_DEVICE_BUSY.
> 
> In theory, you can call blk_run_queue() from the event handler that sees
> the device become ready.  I don't think any driver actually does this,
> but I can't see it would cause any problem.

I will try this. Thanks for your prompt response.

Regards,

K. Y
 

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