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| author | Nathan Huckleberry <nhuck@google.com> | 2023-03-10 11:33:25 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-30 12:47:56 +0200 |
| commit | 0bfadbbcd7a57d5e07bbb9c7af886610276cfeaa (patch) | |
| tree | dbf43930291aa5d0a24719eefc094f4a13829dbc /fs/verity | |
| parent | 992a3f3e8a0c92151dfdf65fc85567c865fd558a (diff) | |
| download | linux-0bfadbbcd7a57d5e07bbb9c7af886610276cfeaa.tar.gz linux-0bfadbbcd7a57d5e07bbb9c7af886610276cfeaa.tar.bz2 linux-0bfadbbcd7a57d5e07bbb9c7af886610276cfeaa.zip | |
fsverity: Remove WQ_UNBOUND from fsverity read workqueue
commit f959325e6ac3f499450088b8d9c626d1177be160 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: 8a1d0f9cacc9 ("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>
Diffstat (limited to 'fs/verity')
| -rw-r--r-- | fs/verity/verify.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/verity/verify.c b/fs/verity/verify.c index 0adb970f4e73..10e41883dfa1 100644 --- a/fs/verity/verify.c +++ b/fs/verity/verify.c @@ -279,15 +279,15 @@ EXPORT_SYMBOL_GPL(fsverity_enqueue_verify_work); int __init fsverity_init_workqueue(void) { /* - * Use an unbound workqueue to allow bios to be verified in parallel - * even when they happen to complete on the same CPU. This sacrifices - * locality, but it's worthwhile since hashing is CPU-intensive. + * Use a high-priority workqueue to prioritize verification work, which + * blocks reads from completing, over regular application tasks. * - * Also use a high-priority workqueue to prioritize verification work, - * which blocks reads from completing, over regular application tasks. + * For performance reasons, don't use an unbound workqueue. Using an + * unbound workqueue for crypto operations causes excessive scheduler + * latency on ARM64. */ fsverity_read_workqueue = alloc_workqueue("fsverity_read_queue", - WQ_UNBOUND | WQ_HIGHPRI, + WQ_HIGHPRI, num_online_cpus()); if (!fsverity_read_workqueue) return -ENOMEM; |