On 03/29/2010 09:20 PM, Chris Wright wrote:
* Badari Pulavarty (pbadari@xxxxxxxxxx) wrote:
I modified my vhost-blk implementation to offload work to
work_queues instead of doing synchronously. Infact, I tried
to spread the work across all the CPUs. But to my surprise,
this did not improve the performance compared to virtio-blk.
I see vhost-blk taking more interrupts and context switches
compared to virtio-blk. What is virtio-blk doing which I
am not able to from vhost-blk ???
Your io wait time is twice as long and your throughput is about half.
I think the qmeu block submission does an extra attempt at merging
requests. Does blktrace tell you anything interesting?
It does. I suggest using fio O_DIRECT random access patterns to avoid
such issues.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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