On Thu, Aug 02, 2012 at 02:43:04PM +0800, Asias He wrote: >> Even if it has a payload waiting is highly suboptimal and it should >> use a non-blocking sequencing like it is done in the request layer. > > So, for REQ_FLUSH, what we need is that send out the VIRTIO_BLK_T_FLUSH and > not to wait. If it's REQ_FLUSH without data a VIRTIO_BLK_T_FLUSH should be sent out only, if it's a REQ_FLUSH that has data a VIRTIO_BLK_T_FLUSH should be sent out, but instead of waiting for it to finish the I/O completion handler should then submit the actual write. > We still need to wait until the actual write is finished here? > Like, > > REQ_FUA is emulated by: > 1. Send the actual write > 2. Wait until the actual write is finished > 3. Send VIRTIO_BLK_T_FLUSH to device > 4. Signal the end of the write to upper layer Remove step 2 and run step 3 from the I/O completion handler. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
