What is the NFS max thread limit

[Eric Browning]

Here is the nfsstat -c output for one mac client for one day from one of my
busy workers.  Are these numbers unreasonable?  There are only 14 retries
which doesn't seem high so I think the network is ok.  Any thoughts on
client side optimizations to reduce RPC load?

Client Info:

RPC Counts:

     Getattr      Setattr       Lookup     Readlink         Read
Write

    72725986         7586        56972           63        17082
22317

      Create       Remove       Rename         Link      Symlink
Mkdir

        4583         2041         3108            0            5
45

       Rmdir      Readdir     RdirPlus       Access        Mknod
Fsstat

         140            0         1106     49382068            0
26197

      Fsinfo     PathConf       Commit

           1            1         3650

RPC Info:

    TimedOut      Invalid    X Replies      Retries     Requests

           0            0            0           14    122252951

Cache Info:

   Attr Hits       Misses    Lkup Hits       Misses    BioR Hits
Misses

   761115632      3278207    110222766        53251    132864002
16282

   BioW Hits       Misses    BioRLHits       Misses    BioD Hits
Misses

      185211        22316        16004           63     12257339
5883

   DirE Hits       Misses

     2990343           23


On Tue, Oct 15, 2013 at 4:41 PM, Rick Macklem <rmacklem at uoguelph.ca> wrote:

> Eric Browning wrote:
> > I'm currently still debugging slow NFS performance on mac clients.
> >  Running
> > 9 stable with a mix of 200 Mac OS X 10.8, 10.7 and 10.6 clients.
> >
> > Periodically I get this error on the mac side:
> > automountd[1766]: set_and_fake_mapent_mntlevel: subdir=/Contents
> > error:
> > Contents not found in map=-fstab
> >
> > I'm wondering with 200 clients with five nfsiod threads (~1000 nfsiod
> > threads total) am I oversubscribing the nfs server?  I can't seem to
> > configure any more than 256 threads (nfs_server_flags="-t -n 256").
> >  When I
> > configure above 256 I get an error about it resetting to 4:
> >
> > Starting nfsd.
> > nfsd: nfsd count 512; reset to 4
> >
> > Tomorrow when all the mac clients have restarted I have changed their
> > nfsiod threads down to 1 each to see if this is indeed the issue.
> >
> Well, normally not all clients would be actively reading/writing files
> concurrently, so I wouldn't expect your load to need more than 256 nfsd
> threads. I also recall that you had a very large Access RPC load and
> Access RPCs are not done by nfsiod threads. (nfsiod threads only do
> readaheads and write behinds for buffer cache blocks of files.)
>
> However, if you do want to try more than 256 nfsd threads, you will
> need to edit nfsd.c and increase MAXNFSDCNT and then rebuild the nfsd
> daemon from these modified sources.
>
> I have no idea what causes the Mac OS X error, but you could try
> posting on one of the Apple mailing lists like
> darwin-kernel at lists.apple.com.
>
> rick
> ps: The nfsd.c in head/current/10.0 also has a "--maxthreads" option
>     that I don't think is limited to MAXNFSDCNT from a glance at the code.
>
> > Thanks in advance,
> > --
> > Eric Browning
> > Systems Administrator
> > 801-984-7623
> >
> > Skaggs Catholic Center
> > Juan Diego Catholic High School
> > Saint John the Baptist Middle
> > Saint John the Baptist Elementary
> > _______________________________________________
> > freebsd-fs at freebsd.org mailing list
> > http://lists.freebsd.org/mailman/listinfo/freebsd-fs
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> >
>



-- 
Eric Browning
Systems Administrator
801-984-7623

Skaggs Catholic Center
Juan Diego Catholic High School
Saint John the Baptist Middle
Saint John the Baptist Elementary