commit f959325e6a upstream.
WQ_UNBOUND causes significant scheduler latency on ARM64/Android. This
is problematic for latency sensitive workloads, like I/O
post-processing.
Removing WQ_UNBOUND gives a 96% reduction in fsverity workqueue related
scheduler latency and improves app cold startup times by ~30ms.
WQ_UNBOUND was also removed from the dm-verity workqueue for the same
reason [1].
This code was tested by running Android app startup benchmarks and
measuring how long the fsverity workqueue spent in the runnable state.
Before
Total workqueue scheduler latency: 553800us
After
Total workqueue scheduler latency: 18962us
[1]: https://lore.kernel.org/all/20230202012348.885402-1-nhuck@google.com/
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Fixes: 8a1d0f9cac ("fs-verity: add data verification hooks for ->readpages()")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230310193325.620493-1-nhuck@google.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
e66f3039c7