On Thu, May 14, 2015 at 10:55:53AM +1000, Dave Chinner wrote: > percpu_counter: batch size aware __percpu_counter_compare() > > From: Dave Chinner <dchinner@xxxxxxxxxx> > > XFS uses non-stanard batch sizes for avoiding frequent global > counter updates on it's allocated inode counters, as they increment > or decrement in batches of 64 inodes. Hence the standard percpu > counter batch of 32 means that the counter is effectively a global > counter. Currently Xfs uses a batch size of 128 so that it doesn't > take the global lock on every single modification. > > However, Xfs also needs to compare accurately against zero, which > means we need to use percpu_counter_compare(), and that has a > hard-coded batch size of 32, and hence will spuriously fail to > detect when it is supposed to use precise comparisons and hence > the accounting goes wrong. > > Add __percpu_counter_compare() to take a custom batch size so we can > use it sanely in XFS and factor percpu_counter_compare() to use it. > > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Please feel free to route the patch however you see fit. Thanks. -- tejun _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
