Re: [Qemu-devel] [PATCH v2] xen_disk: add persistent grant support to xen_disk backend

[Stefano Stabellini]

On Wed, 9 Jan 2013, Roger Pau Monne wrote:
> On 09/01/13 13:48, Stefano Stabellini wrote:
> > On Tue, 8 Jan 2013, Roger Pau Monne wrote:
> >> This protocol extension reuses the same set of grant pages for all
> >> transactions between the front/back drivers, avoiding expensive tlb
> >> flushes, grant table lock contention and switches between userspace
> >> and kernel space. The full description of the protocol can be found in
> >> the public blkif.h header.
> >>
> >> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob_plain;f=xen/include/public/io/blkif.h
> >>
> >> Speed improvement with 15 guests performing I/O is ~450%.
> >>
> >> Signed-off-by: Roger Pau Monné <address@hidden>
> >> Cc: address@hidden
> >> Cc: Stefano Stabellini <address@hidden>
> >> Cc: Anthony PERARD <address@hidden>
> >> ---
> >> Performance comparison with the previous implementation can be seen in
> >> the followign graph:
> >>
> >> http://xenbits.xen.org/people/royger/persistent_read_qemu.png
> >> ---
> >> Changes since v1:
> >>  * Fix coding style issues.
> >>  * Add more comments regarding how ioreq_map works.
> > 
> > The patch looks good now, I only have a very small stylistic comment.
> > 
> > 
> >> +    for (i = 0; i < ioreq->v.niov; i++) {
> >> +        ioreq->v.iov[i].iov_base = page[i] +
> >> +                                   (uintptr_t)ioreq->v.iov[i].iov_base;
> > 
> > ioreq->v.iov[i].iov_base += (uintptr_t)page[i] ?
> 
> True. Would you like to fix that yourself before committing, or do you
> want me to resend?

I'll fix it myself