Date: Fri, 15 Jul 2005 09:12:12 -0700 From: mohans <mohans@yahoo-inc.com> To: Paul Saab <ps@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: [Fwd: Re: cvs commit: src/sys/nfs nfs_common.c nfs_common.h src/sys/nfsclient nfs_socket.c] Message-ID: <20050715161212.GA33629@yahoo-inc.com> In-Reply-To: <42D7D0C4.30408@freebsd.org> References: <42D7D0C4.30408@freebsd.org>
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Hi Alfred, > Ugh, why not do it beforehand to reduce the copy? This looks like > you'll move all this data into a single mbuf, then possibly shift > all the contents, can't you shift the initial mbuf first, THEN > do the pullup? The change aligns (by copying) data left over the mbuf after a pullup is done. The aligned data will be returned on the subsequent call to nfs_dissect(). Post-pullup, dposp points at the byte in the mbuf chain to be returned on the next call to nfs_dissect() and dposp is what we align. There are other ways of doing this too. We could force alignment in nfsm_dissect_xx() if we notice that the data that will be returned is unaligned. I think they are all quite equivalent in terms of expense. My initial reaction was to check for alignment (and force alignment) in either in nfs_dissect() (the macro) or nfsm_dissect_xx(). For now, though, doing the alignment (if necessary) post-pullup in the guts of nfsm_disct() seems the least risky. > > - Fix nfs_clnt_tcp_soupcall() to bcopy() the rpc length out of the > > mbuf (instead of casting m_data to a uint32). > > Also, is bcopy(9) light enough to be used for this purpose or do > we have something to do unaligned reads? The bcopy() is just for copying out the length. mohan
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