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Re: [Qemu-devel] [PATCH v2] xen: use native disk xenbus protocol if poss
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH v2] xen: use native disk xenbus protocol if possible |
Date: |
Tue, 5 Jul 2016 15:55:48 +0100 (BST) |
User-agent: |
Alpine 2.10 (DEB 1266 2009-07-14) |
On Wed, 29 Jun 2016, Anthony PERARD wrote:
> On Wed, Jun 29, 2016 at 05:50:48PM +0200, Juergen Gross wrote:
> > The qdisk implementation is using the native xenbus protocol only in
> > case of no protocol specified at all. As using the explicit 32- or
> > 64-bit protocol is slower than the native one due to copying requests
> > not by memcpy but element for element, this is not optimal.
> >
> > Correct this by using the native protocol in case word sizes of
> > frontend and backend match.
> >
> > Signed-off-by: Juergen Gross <address@hidden>
>
> Reviewed-by: Anthony PERARD <address@hidden>
Added to my queue
> > ---
> > V2: use native protocol in case of unknown protocol specified as
> > requested by Anthony Perard
> > ---
> > hw/block/xen_disk.c | 18 ++++++++++--------
> > 1 file changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
> > index 90aca73..d0aae67 100644
> > --- a/hw/block/xen_disk.c
> > +++ b/hw/block/xen_disk.c
> > @@ -975,14 +975,16 @@ static int blk_connect(struct XenDevice *xendev)
> > blkdev->feature_persistent = !!pers;
> > }
> >
> > - blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
> > - if (blkdev->xendev.protocol) {
> > - if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) == 0)
> > {
> > - blkdev->protocol = BLKIF_PROTOCOL_X86_32;
> > - }
> > - if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) == 0)
> > {
> > - blkdev->protocol = BLKIF_PROTOCOL_X86_64;
> > - }
> > + if (!blkdev->xendev.protocol) {
> > + blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
> > + } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_NATIVE) ==
> > 0) {
> > + blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
> > + } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) ==
> > 0) {
> > + blkdev->protocol = BLKIF_PROTOCOL_X86_32;
> > + } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) ==
> > 0) {
> > + blkdev->protocol = BLKIF_PROTOCOL_X86_64;
> > + } else {
> > + blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
> > }
> >
> > blkdev->sring = xengnttab_map_grant_ref(blkdev->xendev.gnttabdev,
> > --
> > 2.6.6
> >
>
> --
> Anthony PERARD
>
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