[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH 1/3] qemu-xen-traditional: use O_DIRECT to open disk images for IDE



On Tue, 27 Mar 2012, Zhang, Yang Z wrote:
> > > > diff --git a/xenstore.c b/xenstore.c
> > > > index 4c483e2..ac90366 100644
> > > > --- a/xenstore.c
> > > > +++ b/xenstore.c
> > > > @@ -643,7 +643,7 @@ void xenstore_parse_domain_config(int hvm_domid)
> > > >             }
> > > >              pstrcpy(bs->filename, sizeof(bs->filename), params);
> > > >
> > > > -            flags = BDRV_O_CACHE_WB; /* snapshot and write-back */
> > > > +            flags = BDRV_O_NOCACHE;
> > > >              is_readonly = 0;
> > > >              if (pasprintf(&buf, "%s/mode", bpath) == -1)
> > > >                  continue;
> > > Any reason for this change?
> > 
> > performance and correctness: BDRV_O_NOCACHE in QEMU means opening the
> > disk image with O_DIRECT
> Doesn't cache mode have better performance than NOCACHE?

Actually you are correct. I think that this patch should be dropped from
the series. Of course we need O_DIRECT for QDISK otherwise we do loose
correctness but considering that IDE should only be used during
installation it can stay as it is.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.