Ming Lei <ming....@canonical.com> writes:
> Hi Rusty,
Hi Ming!
Sorry, I was on vacation. I'm back and slowly working through
all my mail...
> 1, FIO script
> [global]
> direct=1
> size=128G
> bsrange=${BS}-${BS}
> timeout=60
> numjobs=4
> ioengine=libaio
> iodepth=64
> filename=/dev/vdb #backed by /dev/nullb0, 4 virtqueues per virtio-blk
> group_reporting=1
>
> [f]
> rw=randread
> 5, result
> 5.1 without Rusty's virtio-vring patch
> - BS=4K, throughput: 179K
> - BS=256K, throughput: 27540
(ie. always using indirect)
> 5.2 with Rusty's virtio-vring patch
> - BS=4K, throughput: 173K
> - BS=256K, throughput: 25350
(ie. usually using indirect).
> Looks throughput decreases if BS is 256K in case of your patch.
Interesting. Looks like we're ending up with fewer descs in flight,
though I'm surprised: with 256K blocks I'd expect us to hit the
steady state of "all indirect" almost immediately.
Hmm... I think the heuristic in my patch is flawed. Let me try again,
and get back to you.
Thanks,
Rusty.
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