Re: 4BSD TCP Ethernet Throughput


John Carter (retrac@rice.edu)
Thu, 27 Oct 88 11:08:04 CDT


Van,

    I've made similar measurements on the similar machines, and come to
roughty the same conclusions. My measurements are in the context of
the V operating systems interkernel protocols, but for raw hardware speed
comparisons, this shouldn't matter.

    Between two SUN-3/50 or SUN-3/60's (both with the LANCE interface),
I can sustain about 8.2 Mbps user-to-user performance (not source/chargen,
sink/discard). From a SUN-3/180 (somewhat slower than the 2/180, but
with the same Intel ethernet interface) to a SUN-3/60, I can sustain
slightly more than 6.0 Mbps user-to-user performance. All these
measurements are for 1024 byte data packets, with 80 byte V interkernel
headers (ouch!!!) and 14 byte ethernet headers. Factoring the headers
in, the SUN-3/50 -> SUN-3/50 throughput is 9.0 Mbps and SUN-3/180 ->
SUN-3/50 throughput is 6.5 Mbps. Roughly the same raw numbers...

    The SUN-2/50's (which use the Intel interface, but are significantly
slower) can maintain around 4.7-5.1 Mbps in or out. These are very rough,
since I haven't fully debugged the implementation on the 2's.

    [ The following is opinion and shouldn't be construed as gospel. ]

    I also have only put a little bit of effort into determining the exact
cause of the disparity. I had made the same decision you had regarding
the 82586's DMA ability, namely, it isn't very good (and can only sustain



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