On Mon 15-06-20 19:26:38, Amir Goldstein wrote: > > This patch changes alloc_file_pseudo() to always opt out of fsnotify by > > setting FMODE_NONOTIFY flag so that no check is made for fsnotify watchers > > on pseudo files. This should be safe as the underlying helper for the > > dentry is d_alloc_pseudo which explicitly states that no lookups are ever > > performed meaning that fanotify should have nothing useful to attach to. > > > > The test motivating this was "perf bench sched messaging --pipe". On > > a single-socket machine using threads the difference of the patch was > > as follows. > > > > 5.7.0 5.7.0 > > vanilla nofsnotify-v1r1 > > Amean 1 1.3837 ( 0.00%) 1.3547 ( 2.10%) > > Amean 3 3.7360 ( 0.00%) 3.6543 ( 2.19%) > > Amean 5 5.8130 ( 0.00%) 5.7233 * 1.54%* > > Amean 7 8.1490 ( 0.00%) 7.9730 * 2.16%* > > Amean 12 14.6843 ( 0.00%) 14.1820 ( 3.42%) > > Amean 18 21.8840 ( 0.00%) 21.7460 ( 0.63%) > > Amean 24 28.8697 ( 0.00%) 29.1680 ( -1.03%) > > Amean 30 36.0787 ( 0.00%) 35.2640 * 2.26%* > > Amean 32 38.0527 ( 0.00%) 38.1223 ( -0.18%) > > > > The difference is small but in some cases it's outside the noise so > > while marginal, there is still some small benefit to ignoring fsnotify > > for files allocated via alloc_file_pseudo in some cases. > > > > Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> > > Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx> Thanks for the patch Mel and for review Amir! I've added the patch to my tree with small amendments to the changelog. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
