On Wed, 2018-10-03 at 13:14 -0400, J . Bruce Fields wrote:
> On Mon, Oct 01, 2018 at 10:41:55AM -0400, Trond Myklebust wrote:
> > Simplify the duplicate replay cache by initialising the
> > preallocated
> > cache entry, so that we can use it as a key for the cache lookup.
> >
> > Note that the 99.999% case we want to optimise for is still the one
> > where the lookup fails, and we have to add this entry to the cache,
> > so preinitialising should not cause a performance penalty.
> >
> > Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> > ---
> > fs/nfsd/cache.h | 6 +--
> > fs/nfsd/nfscache.c | 94 ++++++++++++++++++++++------------------
> > ------
> > 2 files changed, 47 insertions(+), 53 deletions(-)
> >
> > diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h
> > index b7559c6f2b97..bd77d5f6fe53 100644
> > --- a/fs/nfsd/cache.h
> > +++ b/fs/nfsd/cache.h
> > @@ -24,13 +24,13 @@ struct svc_cacherep {
> > unsigned char c_state, /* unused, inprog,
> > done */
> > c_type, /* status, buffer
> > */
> > c_secure : 1; /* req came from
> > port < 1024 */
> > - struct sockaddr_in6 c_addr;
> > __be32 c_xid;
> > - u32 c_prot;
> > + __wsum c_csum;
> > u32 c_proc;
> > + u32 c_prot;
> > u32 c_vers;
> > unsigned int c_len;
> > - __wsum c_csum;
> > + struct sockaddr_in6 c_addr;
> > unsigned long c_timestamp;
> > union {
> > struct kvec u_vec;
>
> Unless I've missed something subtle--I'll move this chunk into the
> next
> patch.--b.
Nothing too subtle. The only reason for keeping it in this patch is
because even with the current code, most of the comparisons hit the
c_xid and possibly sometimes the c_csum, so those are the main fields
that you want to try to keep in the same cache line.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
