Re: [PATCH 1/1] Improve kernfs_notify() poll notification latency

From: Greg Kroah-Hartman
Date: Tue Nov 20 2018 - 11:58:49 EST


On Tue, Nov 20, 2018 at 08:14:19AM -0800, Tejun Heo wrote:
> On Thu, Nov 15, 2018 at 09:09:54PM -0500, Radu Rendec wrote:
> > kernfs_notify() does two notifications: poll and fsnotify. Originally,
> > both notifications were done from scheduled work context and all that
> > kernfs_notify() did was schedule the work.
> >
> > This patch simply moves the poll notification from the scheduled work
> > handler to kernfs_notify(). The fsnotify notification still needs to be
> > done from scheduled work context because it can sleep (it needs to lock
> > a mutex).
> >
> > If the poll notification is time critical (the notified thread needs to
> > wake as quickly as possible), it's better to do it from kernfs_notify()
> > directly. One example is calling sysfs_notify_dirent() from a hardware
> > interrupt handler to wake up a thread and handle the interrupt in user
> > space.
> >
> > Signed-off-by: Radu Rendec <radu.rendec@xxxxxxxxx>
>
> Acked-by: Tejun Heo <tj@xxxxxxxxxx>
>
> Greg, can you please route this one?

Sure, I'll queue it up soon...

greg k-h