Il 17/07/2012 10:29, Asias He ha scritto: > So, vhost-blk at least saves ~6 syscalls for us in each request. Are they really 6? If I/O is coalesced by a factor of 3, for example (i.e. each exit processes 3 requests), it's really 2 syscalls per request. Also, is there anything we can improve? Perhaps we can modify epoll and ask it to clear the eventfd for us (would save 2 reads)? Or io_getevents (would save 1)? > I guess you mean qemu here. Yes, in theory, qemu's block layer can be > improved to achieve similar performance as vhost-blk or kvm tool's > userspace virito-blk has. But I think it makes no sense to prevent one > solution becase there is another in theory solution called: we can do > similar in qemu. It depends. Like vhost-scsi, vhost-blk has the problem of a crippled feature set: no support for block device formats, non-raw protocols, etc. This makes it different from vhost-net. So it begs the question, is it going to be used in production, or just a useful reference tool? Paolo -- 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
