Re: [PATCH - resend] VFS: use synchronize_rcu_expedited() in namespace_unlock()

2018-11-05 Thread NeilBrown
On Fri, Oct 05 2018, NeilBrown wrote: > The synchronize_rcu() in namespace_unlock() is called every time > a filesystem is unmounted. If a great many filesystems are mounted, > this can cause a noticable slow-down in, for example, system shutdown. > > The sequence: > mkdir -p /tmp/Mtest/{0..500

Re: [PATCH - resend] VFS: use synchronize_rcu_expedited() in namespace_unlock()

2018-10-04 Thread Paul E. McKenney
On Fri, Oct 05, 2018 at 02:40:02AM +0100, Al Viro wrote: > On Fri, Oct 05, 2018 at 11:27:37AM +1000, NeilBrown wrote: > > > > The synchronize_rcu() in namespace_unlock() is called every time > > a filesystem is unmounted. If a great many filesystems are mounted, > > this can cause a noticable slo

Re: [PATCH - resend] VFS: use synchronize_rcu_expedited() in namespace_unlock()

2018-10-04 Thread NeilBrown
On Fri, Oct 05 2018, Al Viro wrote: > On Fri, Oct 05, 2018 at 11:27:37AM +1000, NeilBrown wrote: >> >> The synchronize_rcu() in namespace_unlock() is called every time >> a filesystem is unmounted. If a great many filesystems are mounted, >> this can cause a noticable slow-down in, for example,

Re: [PATCH - resend] VFS: use synchronize_rcu_expedited() in namespace_unlock()

2018-10-04 Thread Al Viro
On Fri, Oct 05, 2018 at 11:27:37AM +1000, NeilBrown wrote: > > The synchronize_rcu() in namespace_unlock() is called every time > a filesystem is unmounted. If a great many filesystems are mounted, > this can cause a noticable slow-down in, for example, system shutdown. > > The sequence: > mkd

[PATCH - resend] VFS: use synchronize_rcu_expedited() in namespace_unlock()

2018-10-04 Thread NeilBrown
The synchronize_rcu() in namespace_unlock() is called every time a filesystem is unmounted. If a great many filesystems are mounted, this can cause a noticable slow-down in, for example, system shutdown. The sequence: mkdir -p /tmp/Mtest/{0..5000} time for i in /tmp/Mtest/*; do mount -t tmpf