NFS client READ performance on -current

[Rick Macklem]

Garrett Wollman wrote:
> In article <201407151034.54681.jhb at freebsd.org>, jhb at freebsd.org
> writes:
> 
> >Hmm, I am surprised by the m_pullup() behavior that it doesn't just
> >notice that the first mbuf with a cluster has the desired data
> >already
> >and returns without doing anything.
> 
> The specification of m_pullup() is that it returns a *writable* mbuf
> (and thus also that the "length" provided is less than MHLEN).
> Clusters are read-only.
> 
I suspect you already know this, but being nit-picky...
I think the cluster starts out rw, but become M_RDONLY (not M_WRITABLE())
when copied by reference. Since that will happen in TCP before a
segment gets handed to a device driver for transmission, I think it
will always be M_RDONLY in the device driver's output function.

Does that sound correct? rick

> -GAWollman
> 
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