[linux-cifs-client] [PATCH] cifs: implement drop_inode superblock op

[Jeff Layton]

On Thu, 27 May 2010 09:51:40 -0500
Steve French <smfrench at gmail.com> wrote:

> Cached metadata will still be valid for 1 second - do these still have
> dentries pointing to them?
> 

No. If the i_count is 0, then any dentries attached to the inode would
have gone away. These are inodes that are subject to get flushed out of
the cache at any time. This patch just makes that happen sooner.

> On Thu, May 27, 2010 at 8:38 AM, Jeff Layton <jlayton at redhat.com> wrote:
> > On Wed, 26 May 2010 19:19:11 -0400
> > Scott Lovenberg <scott.lovenberg at gmail.com> wrote:
> >
> >>
> >> >> Any rough idea of performance or memory savings (even in something
> >> >> artificial like dbench run)?
> >> >>
> >> >>
> >> > It's more of a memory savings thing. When I mount with -o noserverino
> >> > and run fsstress on the mount, I'd regularly see the size of the
> >> > cifs_inode_cache hit 60M or more (on a client with 1G RAM). With this
> >> > patch in place, it rarely goes over 2M in size.
> >> >
> >> > Eventually, memory pressure will force the size to go down, but if we
> >> > know that they'll never be used again (which is the case with
> >> > noserverino), it's better to go ahead and just free them.
> >> >
> >> >
> >> I take it this overrides the behavior of the vfs_cache_pressure before
> >> the memory pressure makes reclaiming cache necessary?
> >
> > Not exactly. vfs_cache_pressure just governs the way in which the VM
> > subsystem will attempt to free memory when it needs it by changing the
> > preference for flushing inode and dentry caches.
> >
> > This patch just aims to delete inodes that we know will never be used
> > again as soon as their refcount drops to 0.
> >
> > --
> > Jeff Layton <jlayton at redhat.com>
> >
> 
> 
> 
> -- 
> Thanks,
> 
> Steve


-- 
Jeff Layton <jlayton at redhat.com>