* Dan Nelson [080414 20:24] wrote:
> In the last episode (Apr 14), Alfred Perlstein said:
> > * Robert Blayzor [080414 06:07] wrote:
> > > On Apr 14, 2008, at 7:02 AM, Nawfal bin Mohmad Rouyan wrote:
> > > >I'm using TCP and the entry in /etc/fstab on all clients is as below:
> > > >
> > > >build:/usr/ports /usr/ports nfs tcp,intr,nfsv3,-w=32768,-r=32768,rw,noauto 0 0
> > > >build:/usr/src /usr/src nfs tcp,intr,nfsv3,-w=32768,-r=32768,rw,noauto 0 0
> > > >build:/usr/obj /usr/obj nfs tcp,intr,nfsv3,-w=32768,-r=32768,rw,noauto 0 0
> > >
> > > Are -r and -w really needed/useful for TCP mounts?

> >
> > yes.

>
> This is interesting: according to mountnfs() in nfs_vfsops.c, those are
> already the kernel defaults:
>
> if ((argp->flags & NFSMNT_NFSV3) && argp->sotype == SOCK_STREAM) {
> nmp->nm_wsize = nmp->nm_rsize = NFS_MAXDATA;
> } else {
> nmp->nm_wsize = NFS_WSIZE;
> nmp->nm_rsize = NFS_RSIZE;
> }
>
> $ grep nfs_maxdata /sys/nfs/*
> /sys/nfs/nfsproto.h:#define NFS_MAXDATA 32768
>
> But it looks like /sbin/mount_nfs always overrides them to NFS_WSIZE
> and NFS_RSIZE (both 8K) in its nfsdefargs struct.


Yeah, not sure what to make of this.

Using packet size greater than 8k for UDP mounts can really make
your life miserable because a single dropped IP packet will
force retransmit of the whole packet.

In my experience when using TCP it's really good to go to 32k.

--
- Alfred Perlstein
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