4.20-stable review patch. If anyone has any objections, please let me know.
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From: Toke Høiland-Jørgensen toke@redhat.com
commit 5c14a4d05f68415af9e41a4e667d1748d41d1baf upstream.
When we did the original tests for the optimal value of sk_pacing_shift, we came up with 6 ms of buffering as the default. Sadly, 6 is not a power of two, so when picking the shift value I erred on the size of less buffering and picked 4 ms instead of 8. This was probably wrong; those 2 ms of extra buffering makes a larger difference than I thought.
So, change the default pacing shift to 7, which corresponds to 8 ms of buffering. The point of diminishing returns really kicks in after 8 ms, and so having this as a default should cut down on the need for extensive per-device testing and overrides needed in the drivers.
Cc: stable@vger.kernel.org Signed-off-by: Toke Høiland-Jørgensen toke@redhat.com Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/mac80211/main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/mac80211/main.c +++ b/net/mac80211/main.c @@ -615,13 +615,13 @@ struct ieee80211_hw *ieee80211_alloc_hw_ * We need a bit of data queued to build aggregates properly, so * instruct the TCP stack to allow more than a single ms of data * to be queued in the stack. The value is a bit-shift of 1 - * second, so 8 is ~4ms of queued data. Only affects local TCP + * second, so 7 is ~8ms of queued data. Only affects local TCP * sockets. * This is the default, anyhow - drivers may need to override it * for local reasons (longer buffers, longer completion time, or * similar). */ - local->hw.tx_sk_pacing_shift = 8; + local->hw.tx_sk_pacing_shift = 7;
/* set up some defaults */ local->hw.queues = 1;