Date: Wed, 28 Apr 1999 15:04:04 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Bill Paul <wpaul@skynet.ctr.columbia.edu> Cc: hackers@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: NFS Patch #8 for current available - new TCP fixes Message-ID: <199904282204.PAA09667@apollo.backplane.com> References: <199904281327.JAA29467@skynet.ctr.columbia.edu>
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:For parts that don't support arbitrary alignment, you have to copy.
:Now, in some of the drivers that I ported to the alpha, I only copied
:the first small section of the packet in order to get the IP header
:aligned (since failing to do this causes an unaligned access trap in
:the IP code). This is faster than copying the entire packet to fix
:the alignment, but I'm not sure what effect it has on NFS.
:
:-Bill
:
:--
:=============================================================================
:-Bill Paul (212) 854-6020 | System Manager, Master of Unix-Fu
What will happen is that NFS will realign the unaligned mbufs, which
requires a copy. NFS previously copied in-place, but my patch rewrites
that code to copy to a new buffer ( because copying in-place breaks
NFS/TCP ).
We could avoid realigning the mbufs by changing the various NFS 32 bit
read/write macros to operate in 16 bit chunks. This might be the best
solution ultimately.
-Matt
Matthew Dillon
<dillon@backplane.com>
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