Mark McLoughlin wrote:
Hey,

The main patch in this series is 5/6 - it just kills off the
virtio_net tx mitigation timer and does all the tx I/O in the
I/O thread.

Below are the results I got from benchmarking guest->host and
host->guest on my machine.

There's enough numbers there to make anyone blind, but basically
there are results for current kvm-userspace.git, with the
no-tx-timer patch applied and with the drop-the-mutex patch
applied.

Also, I've included results that show what difference some tuning
makes with all the patches applied. The tuning basically just
involves pinning the I/O thread and the netperf/netserver processes
in both the host and guest to two physical CPUs which share a L2
cache.

(Yes, the 1k buffer size results are weird - we think there's a bug
in recent kernels that causes us not to coalesce these small buffers
into a large GSO packet before sending)

Anyway, the results in all their glory:

                                |       guest->host tput     |      host->guest 
tput
  netperf, 10x20s runs (Gb/s)   |    min/ mean/   max/stddev |   min/  mean/   
max/stddev
  
------------------------------+----------------------------+---------------------------
  kvm-userspace.git, 1k         | 0.600/ 0.645/ 0.670/ 0.025 | 5.170/ 5.285/ 
5.470/ 0.087
  kvm-userspace.git, 16k        | 3.070/ 3.350/ 3.710/ 0.248 | 5.950/ 6.374/ 
6.760/ 0.261
  kvm-userspace.git, 65k        | 4.950/ 6.041/ 7.170/ 0.639 | 5.480/ 5.642/ 
5.810/ 0.092

  no tx timer, 1k               | 0.720/ 0.790/ 0.850/ 0.040 | 4.950/ 5.172/ 
5.370/ 0.128
  no tx timer, 16k              | 4.120/ 4.512/ 4.740/ 0.190 | 4.900/ 5.480/ 
6.230/ 0.416
  no tx timer, 65k              | 5.510/ 7.702/ 9.600/ 1.153 | 4.490/ 5.208/ 
5.690/ 0.408

Okay, I don't see 3/6 yet, but does no tx timer mean just no tx timer or no tx timer + handling IO in the IO thread?

Regards,

Anthony Liguori

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