Re: Drivers: scsi: FLUSH timeout

[Bernd Schubert]

On 09/24/2013 02:35 PM, KY Srinivasan wrote:
> > -----Original Message-----
> > From: Jack Wang [mailto:xjtuwjp@xxxxxxxxx]
> > Sent: Tuesday, September 24, 2013 5:08 AM
> > To: KY Srinivasan
> > Cc: Greg KH; linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx;
> > ohering@xxxxxxxx; jbottomley@xxxxxxxxxxxxx; hch@xxxxxxxxxxxxx; linux-
> > scsi@xxxxxxxxxxxxxxx; Mike Christie
> > Subject: Re: Drivers: scsi: FLUSH timeout
> >
> > On 09/21/2013 07:24 AM, KY Srinivasan wrote:
> > > > -----Original Message-----
> > > > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> > > > Sent: Friday, September 20, 2013 1:32 PM
> > > > To: KY Srinivasan
> > > > Cc: linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx;
> > > > ohering@xxxxxxxx; jbottomley@xxxxxxxxxxxxx; hch@xxxxxxxxxxxxx; linux-
> > > > scsi@xxxxxxxxxxxxxxx
> > > > Subject: Re: Drivers: scsi: FLUSH timeout
> > > >
> > > > On Fri, Sep 20, 2013 at 12:32:27PM -0700, K. Y. Srinivasan wrote:
> > > > > The SD_FLUSH_TIMEOUT value is currently hardcoded.
> > > >
> > > > Hardcoded where?  Please, more context.
> > >
> > > This is defined in scsi/sd.h:
> > >
> > > #define SD_FLUSH_TIMEOUT        (60 * HZ)
> > > > > On our cloud, we sometimes hit this timeout. I was wondering if we
> > > > > could make this a module parameter. If this is acceptable, I can send
> > > > > you a patch for this.
> > > >
> > > > A module parameter don't make sense for a per-device value, does it?
> > > Currently, the 60 second timeout is applied across devices. Ideally, I want to be
> > > able to control the FLUSH TIMEOUT as we currently do I/O timeout. If this is
> > > acceptable, I can work on a patch for that as well.
> > >
> > > Regards,
> > >
> > > K. Y
> > > > greg k-h
> > > --
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> > Hi,
> >
> > Back to 2010, Mike(cc-ed) try to add a flush time out interface, similar
> > to what you want here, no idea why it's just ignored?
> > http://www.spinics.net/lists/linux-scsi/msg45017.html
>
> Thanks Jack. Mike, do you know what the concerns were as to why this
> patch was not accepted?

See also this discussion:

http://marc.info/?l=linux-scsi&m=127167679221319&w=2

And retries have been added by commit 
c213e1407be6b04b144794399a91472e0ef92aec


Cheers,
Bernd

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