request for stable (was Re: [PATCH v4 0/5] vsock/virtio: optimizations to increase the throughput)

[Michael S. Tsirkin]

Patches 1,3 and 4 are needed for stable.
Dave, could you queue them there please?

On Wed, Jul 17, 2019 at 01:30:25PM +0200, Stefano Garzarella wrote:
> This series tries to increase the throughput of virtio-vsock with slight
> changes.
> While I was testing the v2 of this series I discovered an huge use of memory,
> so I added patch 1 to mitigate this issue. I put it in this series in order
> to better track the performance trends.
> 
> v4:
> - rebased all patches on current master (conflicts is Patch 4)
> - Patch 1: added Stefan's R-b
> - Patch 3: removed lock when buf_alloc is written [David];
>            moved this patch after "vsock/virtio: reduce credit update messages"
>            to make it clearer
> - Patch 4: vhost_exceeds_weight() is recently introduced, so I've solved some
>            conflicts
> 
> v3: https://patchwork.kernel.org/cover/10970145
> 
> v2: https://patchwork.kernel.org/cover/10938743
> 
> v1: https://patchwork.kernel.org/cover/10885431
> 
> Below are the benchmarks step by step. I used iperf3 [1] modified with VSOCK
> support. As Micheal suggested in the v1, I booted host and guest with 'nosmap'.
> 
> A brief description of patches:
> - Patches 1:   limit the memory usage with an extra copy for small packets
> - Patches 2+3: reduce the number of credit update messages sent to the
>                transmitter
> - Patches 4+5: allow the host to split packets on multiple buffers and use
>                VIRTIO_VSOCK_MAX_PKT_BUF_SIZE as the max packet size allowed
> 
>                     host -> guest [Gbps]
> pkt_size before opt   p 1     p 2+3    p 4+5
> 
> 32         0.032     0.030    0.048    0.051
> 64         0.061     0.059    0.108    0.117
> 128        0.122     0.112    0.227    0.234
> 256        0.244     0.241    0.418    0.415
> 512        0.459     0.466    0.847    0.865
> 1K         0.927     0.919    1.657    1.641
> 2K         1.884     1.813    3.262    3.269
> 4K         3.378     3.326    6.044    6.195
> 8K         5.637     5.676   10.141   11.287
> 16K        8.250     8.402   15.976   16.736
> 32K       13.327    13.204   19.013   20.515
> 64K       21.241    21.341   20.973   21.879
> 128K      21.851    22.354   21.816   23.203
> 256K      21.408    21.693   21.846   24.088
> 512K      21.600    21.899   21.921   24.106
> 
>                     guest -> host [Gbps]
> pkt_size before opt   p 1     p 2+3    p 4+5
> 
> 32         0.045     0.046    0.057    0.057
> 64         0.089     0.091    0.103    0.104
> 128        0.170     0.179    0.192    0.200
> 256        0.364     0.351    0.361    0.379
> 512        0.709     0.699    0.731    0.790
> 1K         1.399     1.407    1.395    1.427
> 2K         2.670     2.684    2.745    2.835
> 4K         5.171     5.199    5.305    5.451
> 8K         8.442     8.500   10.083    9.941
> 16K       12.305    12.259   13.519   15.385
> 32K       11.418    11.150   11.988   24.680
> 64K       10.778    10.659   11.589   35.273
> 128K      10.421    10.339   10.939   40.338
> 256K      10.300     9.719   10.508   36.562
> 512K       9.833     9.808   10.612   35.979
> 
> As Stefan suggested in the v1, I measured also the efficiency in this way:
>     efficiency = Mbps / (%CPU_Host + %CPU_Guest)
> 
> The '%CPU_Guest' is taken inside the VM. I know that it is not the best way,
> but it's provided for free from iperf3 and could be an indication.
> 
>         host -> guest efficiency [Mbps / (%CPU_Host + %CPU_Guest)]
> pkt_size before opt   p 1     p 2+3    p 4+5
> 
> 32         0.35      0.45     0.79     1.02
> 64         0.56      0.80     1.41     1.54
> 128        1.11      1.52     3.03     3.12
> 256        2.20      2.16     5.44     5.58
> 512        4.17      4.18    10.96    11.46
> 1K         8.30      8.26    20.99    20.89
> 2K        16.82     16.31    39.76    39.73
> 4K        30.89     30.79    74.07    75.73
> 8K        53.74     54.49   124.24   148.91
> 16K       80.68     83.63   200.21   232.79
> 32K      132.27    132.52   260.81   357.07
> 64K      229.82    230.40   300.19   444.18
> 128K     332.60    329.78   331.51   492.28
> 256K     331.06    337.22   339.59   511.59
> 512K     335.58    328.50   331.56   504.56
> 
>         guest -> host efficiency [Mbps / (%CPU_Host + %CPU_Guest)]
> pkt_size before opt   p 1     p 2+3    p 4+5
> 
> 32         0.43      0.43     0.53     0.56
> 64         0.85      0.86     1.04     1.10
> 128        1.63      1.71     2.07     2.13
> 256        3.48      3.35     4.02     4.22
> 512        6.80      6.67     7.97     8.63
> 1K        13.32     13.31    15.72    15.94
> 2K        25.79     25.92    30.84    30.98
> 4K        50.37     50.48    58.79    59.69
> 8K        95.90     96.15   107.04   110.33
> 16K      145.80    145.43   143.97   174.70
> 32K      147.06    144.74   146.02   282.48
> 64K      145.25    143.99   141.62   406.40
> 128K     149.34    146.96   147.49   489.34
> 256K     156.35    149.81   152.21   536.37
> 512K     151.65    150.74   151.52   519.93
> 
> [1] https://github.com/stefano-garzarella/iperf/
> 
> Stefano Garzarella (5):
>   vsock/virtio: limit the memory used per-socket
>   vsock/virtio: reduce credit update messages
>   vsock/virtio: fix locking in virtio_transport_inc_tx_pkt()
>   vhost/vsock: split packets to send using multiple buffers
>   vsock/virtio: change the maximum packet size allowed
> 
>  drivers/vhost/vsock.c                   | 68 ++++++++++++-----
>  include/linux/virtio_vsock.h            |  4 +-
>  net/vmw_vsock/virtio_transport.c        |  1 +
>  net/vmw_vsock/virtio_transport_common.c | 99 ++++++++++++++++++++-----
>  4 files changed, 134 insertions(+), 38 deletions(-)
> 
> -- 
> 2.20.1