On Mon, Dec 01, 2014 at 09:16:41AM +0100, David Hildenbrand wrote: > > Based on patch by Cornelia Huck. > > > > Note: for consistency, and to avoid sparse errors, > > convert all fields, even those no longer in use > > for virtio v1.0. > > > > Signed-off-by: Cornelia Huck <cornelia.h...@de.ibm.com> > > Signed-off-by: Michael S. Tsirkin <m...@redhat.com> > ... > > > > -static unsigned int features[] = { > > +static unsigned int features_legacy[] = { > > VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, > > VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI, > > VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE, > > VIRTIO_BLK_F_MQ, > > +} > > +; > > +static unsigned int features[] = { > > + VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, > > + VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, > > + VIRTIO_BLK_F_TOPOLOGY, > > + VIRTIO_BLK_F_MQ, > > + VIRTIO_F_VERSION_1, > > We can fit this into less lines, like done for features_legacy. > > I was asking myself if we could do the conversion of the statical values > somehow upfront, to reduce the patch size and avoid cpu_to_virtio.* at those > places. > > Otherwise looks good to me. >
I don't see how we can reduce the patch size. For BE architectures it's dynamic, so at best the values will become macros/incline functions taking a flag. For some places on data path, it might be worth it to cache the correct value e.g. as part of device structure. This replaces a branch with a memory load, so the gain would have to be measured, best done separately? -- MST _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization