Recent AMD760MPX chipset PCI measurements??

Joachim Worringen joachim at lfbs.RWTH-Aachen.DE
Fri Feb 8 03:46:09 EST 2002


Paul Lu wrote:

>         DMA rate for 4096 Byte transfers (64bit / 66MHz bus)
>         1st: 8 pages from bogus sdma pg, 8 to bogus rdma
>                 bus_read  (send) = 315 MBytes/s
>                 bus_write (recv) = 341 MBytes/s
> 
> which is a bit disappointing.  I guess the numbers are not outright
> horrible, but they are not nearly as good as the Serverworks-based boards
> we have now (yes, this may be an apples-oranges thing :-)

Depending on what you intend to use your PCI-bus for (I assume for the
interconnect?), this bandwidth may well be enough. I.e., Myrinet has 2Gb
links, and thus the bottleneck when using a Myrinet board in this bus is
the network link, not the PCI bus. Ohter interconnects (like SCI with
6.4Gb) have higher link-layer bandwidth, but also for those the
bottleneck on real-world applications is not the 64bit-PCI bus if it
delivers 300 MB/s (it's things like the local memory bandwidth, DMA
buffer preparation, network links & switches, inter-process
synchronization delay etc.).

  Joachim

-- 
|  _  RWTH|  Joachim Worringen
|_|_`_    |  Lehrstuhl fuer Betriebssysteme, RWTH Aachen
  | |_)(_`|  http://www.lfbs.rwth-aachen.de/~joachim
    |_)._)|  fon: ++49-241-80.27609 fax: ++49-241-80.22339
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