Re: spinlocks on HP-UX

"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> Robert Haas <robertmhaas@gmail.com> wrote:
>> Stepping beyond the immediate issue of whether we want an unlocked
>> test in there or not (and I agree that based on these numbers we
>> don't), there's a clear and puzzling difference between those sets
>> of numbers.  The Opteron test is showing 32 clients getting about
>> 23.9 times the throughput of a single client, which is not exactly
>> linear but is at least respectable, whereas the PPC64 test is
>> showing 32 clients getting just 14.5 times the throughput of a
>> single client, which is pretty significantly less good.
> I wouldn't make too much of that without comparing to a STREAM test
> (properly configured -- the default array size is likely not to be
> large enough for these machines).

Yeah.  One point I didn't mention is that the Opteron machine's memory
is split across 8 NUMA nodes, whereas the PPC machine's isn't.  I would
bet there's a significant difference in aggregate available memory
bandwidth.

Also, if the PPC machine really is hyperthreaded (the internal webpage
for it says "Hyper? True" but /proc/cpuinfo doesn't provide any clear
indications), that might mean it's not going to scale too well past 16x
the single-thread case.
        regards, tom lane