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From: David Malone <dwmalone@FreeBSD.org>
Date: Mon, 24 Jul 2006 15:42:04 +0000 (UTC)
To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org
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Subject: cvs commit: src/sys/net bpf.c
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dwmalone    2006-07-24 15:42:04 UTC

  FreeBSD src repository

  Modified files:
    sys/net              bpf.c 
  Log:
  Rather than calling mircotime() in catchpacket(), make catchpacket()
  take a timeval indicating when the packet was captured. Move
  microtime() to the calling functions and grab the timestamp as soon
  as we know that we're going to call catchpacket at least once.
  
  This means that we call microtime() once per matched packet, as
  opposed to once per matched packet per bpf listener. It also means
  that we return the same timestamp to all bpf listeners, rather than
  slightly different ones.
  
  It would be more accurate to call microtime() even earlier for all
  packets, as you have to grab (1+#listener) locks before you can
  determine if the packet will be logged. You could always grab a
  timestamp before the locks, but microtime() can be costly, so this
  didn't seem like a good idea.
  
  (I guess most ethernet interfaces will have a bpf listener these
  days because of dhclient. That means that we could be doing two bpf
  locks on most packets going through the interface.)
  
  PR:             71711
  
  Revision  Changes    Path
  1.170     +30 -6     src/sys/net/bpf.c