Re: more profiling

On Tue, Sep 19, 2006, Andres Kroonmaa wrote:

> Is that all? or did you paste only part of probes?
> When I used it on my prod caches, I enabled quite alot
> more probes. When the profiling feature was included,
> there were other concurrent changes (eg chunked mempools)
> and in submitted patch many probes got left out.

Only part of the probing.

> Since then quite alot of changes have happened, so I'd
> suggest to look at the gprof stats to decide what funcs
> to probe with hires prof and add them.

Yeah, I'm thinking that too.

> Also review the probes already there - you'd want to make
> sure a probe isn't left "running" at any function exit
> point - this would lead to accounting to a probe sections
> of code incorrectly.
>
> There's something fishy with "best case" timers. They
> shouldn't be zero, ever. Ditto "worst case" - they *can*
> get high due to task switches, but your worst cases look
> way too high, on P4 2.6G there should be 2.6G ticks per
> second. Your worst case looks like probes have been
> running for 8.9secs straight, seems unlikely.
> So there seems to be a need to get hires profiling
> uptodate with current squid code base.

I did notice that but I don't know enough about the code to go digging.
That said, the traces look much nicer now. There's definitely something
weird going on with the nested traces though.

I just don't have the time to go through the profiling code. Its definitely
nicer to use than gprof but it'd be nice to keep counts of call graphs.
Thats all I really use gprof for these days.

> Unfortunately, I can't participate for now, my company
> has been restructured and caching has been thrown out, so
> I don't have any suitable platform at the moment.. ;(

My current employer is responsible for a few Squid caches here and
there but they're small installs for < 100 people. Squid-2.6 is a
negligible load on the proxy servers.

I'm doing all this stuff for fun. I got sick of having no hardware
and bought some second-hand equipment to play with.

adrian
Received on Tue Sep 19 2006 - 05:55:51 MDT