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| author | Willem de Bruijn <willemb@google.com> | 2019-06-13 12:24:57 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-06-14 19:34:27 -0700 |
| commit | 31c03aef9bc22a64a8324d650ca4198819ef3a33 (patch) | |
| tree | f899165551f74efdad63d2542c0e21ecb22dfbb9 /drivers/net/virtio_net.c | |
| parent | 87f373921c4ed770abdb3cdafd796ef7f7b86620 (diff) | |
| download | linux-31c03aef9bc22a64a8324d650ca4198819ef3a33.tar.gz linux-31c03aef9bc22a64a8324d650ca4198819ef3a33.tar.bz2 linux-31c03aef9bc22a64a8324d650ca4198819ef3a33.zip | |
virtio_net: enable napi_tx by default
NAPI tx mode improves TCP behavior by enabling TCP small queues (TSQ).
TSQ reduces queuing ("bufferbloat") and burstiness.
Previous measurements have shown significant improvement for
TCP_STREAM style workloads. Such as those in commit 86a5df1495cc
("Merge branch 'virtio-net-tx-napi'").
There has been uncertainty about smaller possible regressions in
latency due to increased reliance on tx interrupts.
The above results did not show that, nor did I observe this when
rerunning TCP_RR on Linux 5.1 this week on a pair of guests in the
same rack. This may be subject to other settings, notably interrupt
coalescing.
In the unlikely case of regression, we have landed a credible runtime
solution. Ethtool can configure it with -C tx-frames [0|1] as of
commit 0c465be183c7 ("virtio_net: ethtool tx napi configuration").
NAPI tx mode has been the default in Google Container-Optimized OS
(COS) for over half a year, as of release M70 in October 2018,
without any negative reports.
Link: https://marc.info/?l=linux-netdev&m=149305618416472
Link: https://lwn.net/Articles/507065/
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/virtio_net.c')
| -rw-r--r-- | drivers/net/virtio_net.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0d4115c9e20b..4f3de0ac8b0b 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -26,7 +26,7 @@ static int napi_weight = NAPI_POLL_WEIGHT; module_param(napi_weight, int, 0444); -static bool csum = true, gso = true, napi_tx; +static bool csum = true, gso = true, napi_tx = true; module_param(csum, bool, 0444); module_param(gso, bool, 0444); module_param(napi_tx, bool, 0644); |