On Fri, Jan 10, 2020 at 4:04 PM Dr. David Alan Gilbert <dgilb...@redhat.com> wrote: > > * Daniel P. Berrangé (berra...@redhat.com) wrote: > > On Thu, Dec 12, 2019 at 04:38:28PM +0000, Dr. David Alan Gilbert (git) > > wrote: > > > From: Miklos Szeredi <mszer...@redhat.com> > > > > > > > What is readdirplus and what do we need a command line option to > > control it ? What's the user benefit of changing the setting ? > > cc'ing Miklos who understands this better than me. > > My understanding is that readdirplus is a heuristic inherited from NFS > where when you iterate over the directory you also pick up stat() data > for each entry in the directory. You then cache that stat data > somewhere. > The Plus-ness is that a lot of directory operations involve you stating > each entry (e.g. to figure out if you can access it etc) so rolling it > into one op avoids the separate stat. The unplus-ness is that it's an > overhead and I think changes some of the caching behaviour.
Yeah, so either may give better performance and it's hard to pick a clear winner. NFS also has an option to control this. Thanks, Miklos
