DragonFly BSD
DragonFly commits List (threaded) for 2004-10
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cvs commit: src/sys/dev/netif/em

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 18 Oct 2004 22:47:52 -0700 (PDT)

dillon      2004/10/18 22:47:52 PDT

DragonFly src repository

  Modified files:
    sys/dev/netif/em     if_em.c 
  MFC FreeBSD if_em.c 1.48 and 1.49.
  Remove an unnecessary bus_dmamap_create and destroy for the rx and tx
  descriptor rings.  No bounce buffers are ever needed since bus_dmamem_alloc()
  allocates the correct type of memory and never needs a bounce buffer.
  Use an alignment of 1 instead of PAGE_SIZE for the rx and tx buffer tags.
  Since the e1000 DMA engines hava no constraints on the alignment of buffer
  transfers, there is no reason to tell busdma that there is.  This saves a
  minimum of 1 malloc call per packet and avoids needless boucning.
  Use BUS_DMA_WAITOK when allocating the receive descriptor ring.  It's really
  silly to use BUS_DMA_NOWAIT here, it isn't all that much memory.
  A simple cached NFS test did not result in any noticeable improvement in
  cpu or packet efficiency but Scott's commit message indicated a significant
  improvement in a larger FreeBSD machine setup, probably oweing more to the
  locks eliminated in FreeBSD (which does not apply to DragonFly).
  Suggested-by: David Rhodus
  Obtained from: Sandvine, Inc.  via FreeBSD  if_em.c 1.48 and 1.49 (scottl)
  Revision  Changes    Path
  1.20      +1 -11     src/sys/dev/netif/em/if_em.c


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