Processor contention(?) and network bandwidth on AMD
jlb17 at duke.edu
Mon Apr 29 17:22:41 EDT 2002
On Mon, 29 Apr 2002 at 5:07pm, Robert G. Brown wrote
> Try this:
> Do your netpipe transmitter on an unloaded host, a host at load 1 and
> at load 2.
> Do your netpipe receiver on an unloaded host, a host at load 1 and one
> at load 2.
> Fill in the matrix -- load 0 to load 0, load 0 to load 1, etc.
> I found (in similar tests done years ago) that a TRANSMITTER could be
> loaded to 2 (per cpu) with only a small degradation of throughput, but
> loading a RECEIVER would drop throughput dramatically, by as much as
I will indeed do these tests and post a followup. One thing, though, that
I don't know that I made clear. I understand and accept that a higher
load is going to affect bandwidth. What I'm pointing out (and wondering
why) is that the effect is *far* greater on dual AMD based systems than it
is on, e.g., the dual PIII systems I have.
As an aside, At Mark's suggestion, I reniced the ksoftirqds on a S2466
based system, and saw vast improvement. For no load, 2 matlabs, and 2
matlabs+2SETIs I saw (with the cursed 2.4.9-31 RH kernel):
ksoftirqds reniced to 0:
11463.5 KB/real sec
10637 KB/real sec
9585.39 KB/real sec
And reniced to -19:
11481.8 KB/real sec
10632.7 KB/real sec
9347.31 KB/real sec
Department of Biomedical Engineering
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