RE: [PATCH 1/1] Staging: hv: storvsc: Move the storage driver outof the staging area

[KY Srinivasan]

> -----Original Message-----
> From: James Bottomley [mailto:James.Bottomley@xxxxxxxxxxxxxxxxxxxxx]
> Sent: Friday, November 18, 2011 12:01 PM
> To: KY Srinivasan
> Cc: gregkh@xxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxx; linux-
> scsi@xxxxxxxxxxxxxxx; ohering@xxxxxxxx; hch@xxxxxxxxxxxxx
> Subject: RE: [PATCH 1/1] Staging: hv: storvsc: Move the storage driver out of the
> staging area
> 
> On Fri, 2011-11-18 at 04:53 +0000, KY Srinivasan wrote:
> > > I still think you need to disable clustering and junk the bvec merge
> > > function.  Your object seems to be to accumulate in page size multiples
> > > (and not aggregate over this) ... that's what clustering is designed to
> > > do.
> >
> > As part of addressing your first round of comments, I experimented with your
> > suggestions and I could not get rid of the code that does the bounce buffer
> handling.
> > I could generate I/O patterns that would require bounce buffer handling with
> your
> > suggestions in place.
> 
> There are two separate things here.  One is the scatter gather list
> bounce buffer processing, which is a bit nasty, but if you want to use <
> 4kb block size filesystems, I suppose I have to accept that you need it
> (although since it's a global fault of the hypervisor, perhaps it should
> sit in the hypervisor interface layer, so that every SG based transport
> can use it).  The other is the biovec merge function addition.  The
> purpose of this function seems to be to ensure you get one SG entry for
> every page (if I read it right)?  In that case, you don't need any of
> this special casing.  The flag DISABLE_CLUSTERING achieves the same
> thing.

Thanks James. I will keep you posted on my progress on this issue.

Regards,

K. Y

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