Re: [PATCH] vhost: Add polling mode

Razya Ladelsky
2014-07-29T12:24:04Z

>
> Hmm there aren't a lot of numbers there :(. Speed increased by 33% but
> by how much? E.g. maybe you are getting from 1Mbyte/sec to 1.3,
> if so it's hard to get excited about it.

Netperf 1 VM: 1516 MB/sec -> 2046 MB/sec
and for 3 VMs: 4086 MB/sec -> 5545 MB/sec

> Some questions that come to
> mind: what was the message size? I would expect several measurements
> with different values. How did host CPU utilization change?
>

message size was 64B in order to get the VM to be cpu saturated.
so vhost had 99% cpu and vhost 38%, with the polling patch both had 99%.

> What about latency? As we are competing with guest for host CPU,
> would worst-case or average latency suffer?
>

Polling indeed doesn't make a lot of sense if there aren't enough
available cores.
In these cases polling should not be used.

Thank you,
Razya

> Thanks,
>
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