On Fri 01-02-19 09:19:04, Dave Chinner wrote: > Maybe for memcgs, but that's exactly the oppose of what we want to > do for global caches (e.g. filesystem metadata caches). We need to > make sure that a single, heavily pressured cache doesn't evict small > caches that lower pressure but are equally important for > performance. > > e.g. I've noticed recently a significant increase in RMW cycles in > XFS inode cache writeback during various benchmarks. It hasn't > affected performance because the machine has IO and CPU to burn, but > on slower machines and storage, it will have a major impact. Just as a data point, our performance testing infrastructure has bisected down to the commits discussed in this thread as the cause of about 40% regression in XFS file delete performance in bonnie++ benchmark. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
