Messages in this thread | | | Date | Tue, 23 Nov 2021 07:44:45 +0100 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] kernfs: switch global kernfs_rwsem lock to per-fs lock |
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On Mon, Nov 22, 2021 at 09:39:28AM -0800, Minchan Kim wrote: > On Thu, Nov 18, 2021 at 01:03:32PM -1000, Tejun Heo wrote: > > On Thu, Nov 18, 2021 at 03:00:08PM -0800, Minchan Kim wrote: > > > The kernfs implementation has big lock granularity(kernfs_rwsem) so > > > every kernfs-based(e.g., sysfs, cgroup) fs are able to compete the > > > lock. It makes trouble for some cases to wait the global lock > > > for a long time even though they are totally independent contexts > > > each other. > > > > > > A general example is process A goes under direct reclaim with holding > > > the lock when it accessed the file in sysfs and process B is waiting > > > the lock with exclusive mode and then process C is waiting the lock > > > until process B could finish the job after it gets the lock from > > > process A. > > > > > > This patch switches the global kernfs_rwsem to per-fs lock, which > > > put the rwsem into kernfs_root. > > > > > > Suggested-by: Tejun Heo <tj@kernel.org> > > > Signed-off-by: Minchan Kim <minchan@kernel.org> > > > > Acked-by: Tejun Heo <tj@kernel.org> > > > > Greg, I think this is the right thing to do even if there is no concrete > > performance argument (not saying there isn't). It's just weird to entangle > > these completely unrelated users in a single rwsem. > > > > Thanks. > > Greg, Do you mind picking this patch?
$ mdfrm -c ~/mail/todo/ 1872 messages in /home/gregkh/mail/todo/
Give me a chance to catch up...
thanks,
greg k-h
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