On Wed, Feb 27, 2019 at 11:08:07AM +0100, Toke Høiland-Jørgensen wrote:
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.
Stable backport moves the change to where the value was set before the addition of per-device override support in 4.20.
Now queued up, thanks.
greg k-h