Anton Blanchard wrote:
| > > There's several things where per cpu data is useful; low frequency
| > > statistics is not one of them in my opinion.
| >
| > ...which may be true for 4-ways and even 8-ways but when you get to
| > 32-ways and greater, you start seeing cache problems. That was the
| > case on AIX and per-cpu counters was one of the changes that helped
| > get the spectacular scalability on Regatta.
|
| I agree there are large areas of improvement to be done wrt cacheline
| ping ponging (see my patch in 2.4.17-pre6 for one example), but we
| should do our own benchmarking and not look at what AIX has been doing.
Oh, please! You voiced an opinion. I presented facts. Nobody suggested
we should not measure on Linux. As a matter of fact, I suggested that
Kiran does tests on the real counters and he said he would.
Niels
> | > ...which may be true for 4-ways and even 8-ways but when you get to
> | > 32-ways and greater, you start seeing cache problems. That was the
> | > case on AIX and per-cpu counters was one of the changes that helped
> | > get the spectacular scalability on Regatta.
> |
> | I agree there are large areas of improvement to be done wrt cacheline
> | ping ponging (see my patch in 2.4.17-pre6 for one example), but we
> | should do our own benchmarking and not look at what AIX has been doing.
>
> Oh, please! You voiced an opinion. I presented facts. Nobody suggested
> we should not measure on Linux. As a matter of fact, I suggested that
> Kiran does tests on the real counters and he said he would.
Exactly, show me where the current problem is and I will benchmark it on
a 16 way linux/ppc64 machine. Your comments are opinions too unless
you have some figures to back them up :)
Anton