On 07/05/12 17:53, Bart Van Assche wrote: > On 07/05/12 01:52, Nicholas A. Bellinger wrote: >> fio randrw workload | virtio-scsi-raw | virtio-scsi+tcm_vhost | bare-metal >> raw block >> ------------------------------------------------------------------------------------ >> 25 Write / 75 Read | ~15K | ~45K | ~70K >> 75 Write / 25 Read | ~20K | ~55K | ~60K > > These numbers are interesting. To me these numbers mean that there is a > huge performance bottleneck in the virtio-scsi-raw storage path. Why is > the virtio-scsi-raw bandwidth only one third of the bare-metal raw block > bandwidth ?
(replying to my own e-mail) Or maybe the above numbers mean that in the virtio-scsi-raw test I/O was serialized (I/O depth 1) while the other two tests use a large I/O depth (64) ? It can't be a coincidence that the virtio-scsi-raw results are close to the bare-metal results for I/O depth 1. Another question: which functionality does tcm_vhost provide that is not yet provided by the SCSI emulation code in qemu + tcm_loop ? Bart. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
