From owner-cvs-all  Mon Dec 10 19: 2:55 2001
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From: Luigi Rizzo <luigi@FreeBSD.org>
Date: Mon, 10 Dec 2001 19:02:48 -0800 (PST)
To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: cvs commit: src/sys/pci if_dc.c
X-FreeBSD-CVS-Branch: RELENG_4
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luigi       2001/12/10 19:02:48 PST

  Modified files:        (Branch: RELENG_4)
    sys/pci              if_dc.c 
  Log:
  MFC (done now because the code is slightly different from the one
  in -current):  avoid an unnecessary copy when the packet is already
  in a single buffer.
  
  With this one-line patch, a 750MHz box goes from 128kpps to 148kpps
  (full wire speed) even with NICs that require packets in a single mbuf.
  
  Trivia: the 21143, which can handle multiple buffers, seems to
  introduce extra delay between packets when they are split over
  multiple tx descriptors. So if you are in this situation and have
  CPU cycles to burn, doing the copy is the only way to achieve wire
  speed (short of arranging tx descriptors as an array instead of a
  linked list).
  
  Revision  Changes    Path
  1.9.2.30  +3 -1      src/sys/pci/if_dc.c

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