On Mon, Apr 04, 2005 at 04:43:21PM -0700, Roland Dreier wrote:
> A binary search to find the changeset that makes the difference would
> be really useful. I read through the svn log from r2046 through r2082
> and I don't see anything that should make a difference to IPoIB.
I've worked backwards and didn't see any changes with netperf TCP_STREAM.
I can't establish why the perfomance is substantially
different with r2050 compared to before:
SVN Rev Best Worst
r2104-MSIX 3609 2623
r2081-MSIX 3580 2639
r2062-MSIX 3609 2618
r2054-MSIX 3602 2635
r2050-MSIX 3598 2636
r2050-IRQ 3594 2433
r2050-orig 1738(*)
Numbers are in Mbits/s. 3600 is ~450 MB/s. 2600 is ~325 MB/s.
Differences between Best/Worst are caused by binding netperf and
netserver to the same (or different) CPU as the one handling
interrupts. See "-T" in netperf 2.4.0-rc1 "experimental"
release.
(*) I didn't use -T with netperf to explore IRQ assignment.
I think differences in "Best" column are not significant.
(Except for the r2050-orig number of course...)
...
> So I wonder what obvious thing I'm missing...
I'm using gcc-3.3.5 (Debian 1:3.3.5-8) now and may have used gcc 3.4
or a slightly older gcc-3.3. I might be confusing gcc version
with other work I've done too. I'm of course kicking myself for being
sloppy and not tracking that precisely.
I'm also using s different version of netperf (2.4.0-rc1).
But I don't expect substantial changes in TCP_STREAM implementation
that might cause 2x difference in performance.
TCP_STREAM test is "mature" code.
My best/worst theory right now is the TS90 switch was in a semi-comatose
state when I collected the perf numbers in January. When I tried to collect
perf data in March, the TS90 switch was non-responsive at the serial
console and a power cycle took care of that. I hadn't cycled power
on the switch since installing it in June 2004 or so.
thanks,
grant
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