On Fri, Mar 17, 2017 at 1:34 AM, Changpeng Liu <changpeng.liu@xxxxxxxxx> wrote: > Currently virtio_blk driver does not provide discard feature > flag, so the filesystems which built on top of the block device > will not send discard command. This is okay for HDD backend, but > it will impact the performance for SSD backend. > > Add a feature flag such as VIRTIO_BLK_F_DISCARD to virtio_blk driver > is very straightforward, but it will extend the exist virtio_blk > protocol, I'm preparing to add this feature, before that, I'd like > to get comments or suggestions from community. Please remember to also send a VIRTIO spec change: https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio#feedback This feature was not added to virtio-blk in the past because virtio-scsi was essentially a replacement that could support all disk I/O features (thanks to the SCSI command set). There are many virtio-blk users and some may not want to migrate to virtio-scsi. So it seems reasonable to add a DISCARD command to virtio-blk. Stefan _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
