On 2014-06-25 20:08, Ming Lei wrote:
Hi, These patches try to support multi virtual queues(multi-vq) in one virtio-blk device, and maps each virtual queue(vq) to blk-mq's hardware queue. With this approach, both scalability and performance on virtio-blk device can get improved. For verifying the improvement, I implements virtio-blk multi-vq over qemu's dataplane feature, and both handling host notification from each vq and processing host I/O are still kept in the per-device iothread context, the change is based on qemu v2.0.0 release, and can be accessed from below tree: git://kernel.ubuntu.com/ming/qemu.git #v2.0.0-virtblk-mq.1 For enabling the multi-vq feature, 'num_queues=N' need to be added into '-device virtio-blk-pci ...' of qemu command line, and suggest to pass 'vectors=N+1' to keep one MSI irq vector per each vq, and the feature depends on x-data-plane. Fio(libaio, randread, iodepth=64, bs=4K, jobs=N) is run inside VM to verify the improvement. I just create a small quadcore VM and run fio inside the VM, and num_queues of the virtio-blk device is set as 2, but looks the improvement is still obvious. 1), about scalability - without mutli-vq feature -- jobs=2, thoughput: 145K iops -- jobs=4, thoughput: 100K iops - with mutli-vq feature -- jobs=2, thoughput: 193K iops -- jobs=4, thoughput: 202K iops 2), about thoughput - without mutli-vq feature -- thoughput: 145K iops - with mutli-vq feature -- thoughput: 202K iops
Of these numbers, I think it's important to highlight that the 2 thread case is 33% faster and the 2 -> 4 thread case scales linearly (100%) while the pre-patch case sees negative scaling going from 2 -> 4 threads (-39%).
I haven't run your patches yet, but from looking at the code, it looks good. It's pretty straightforward. See feel free to add my reviewed-by.
Rusty, do you want to ack this (and I'll slurp it up for 3.17) or take this yourself? Or something else?
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