On 1/9/24 12:48 PM, Amir Goldstein wrote:
> Commit e43de7f0862b ("fsnotify: optimize the case of no marks of any type")
> optimized the case where there are no fsnotify watchers on any of the
> filesystem's objects.
>
> It is quite common for a system to have a single local filesystem and
> it is quite common for the system to have some inotify watches on some
> config files or directories, so the optimization of no marks at all is
> often not in effect.
>
> Access event watchers are far less common, so optimizing the case of
> no marks with access events could improve performance for more systems,
> especially for the performance sensitive hot io path.
>
> Maintain a per-sb counter of objects that have marks with access
> events in their mask and use that counter to optimize out the call to
> fsnotify() in fsnotify access hooks.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
>
> Jens,
>
> You may want to try if this patch improves performance for your workload
> with SECURITY=Y and FANOTIFY_ACCESS_PERMISSIONS=Y.
Ran the usual test, and this effectively removes fsnotify from the
profiles, which (as per other email) is between 5-6% of CPU time. So I'd
say it looks mighty appealing!
--
Jens Axboe
