[Xorp-hackers] PATCH: Enable libxipc tests

Bruce Simpson bms at incunabulum.net
Thu Nov 26 14:04:33 PST 2009


Ben Greear wrote:
>
> Can you run perf tests with what you've checked in so far?
Thanks for doing this, this is the meat I need just now.
Not yet. I'm just about to merge your stuff for receiver/sender shortly.

I was up fairly late last night assessing tools.

It looks like 'mpatrol' is still king of the heap profilers. Valgrind 
looked to have swallowed it; its error messages are very similar.

I found Google Performance Tools forces you to use their tcmalloc, which 
probably doesn't yield correct results about the behaviour of the malloc 
on a typical system. FreeBSD's jemalloc can  generate ktrace records, 
but this has syscall overhead.

The main reason I'm looking at heap profiling, is because Marko Zec, who 
worked on XRL performance a few years ago, hinted strongly that 
allocations were the source of XRL's slowness on the hot path BGP-RIB-FEA.

He didn't have conclusive figures, but the oprofile dump you posted 
hints at that; the CPU's tied up in libstdc++, probably the allocator.

Re function profiling: I am getting around to those changes. At the 
moment, Function Check (fnccheck) looks as though it is a bit stronger 
than gprof, and KProf can digest output from both of them:
    http://www.freshports.org/devel/fnccheck/
    http://kprof.sourceforge.net/

If you have an AMD Linux box handy, AMD CodeAnalyzer looks like it's 
worth a shot; it does all the ELF/DWARF lookup, graphing, cache and 
cycle profiling, etc.
I have a spare amd64 lying around, if I can find time, I may try it 
under Fedora (which seems to have better packaging for it).

DTrace is king of the non-invasive tap, but there is no pid provider 
support in FreeBSD yet. All of the Sun examples for tracing userland 
calls need the pid provider.

"The Malloc Wars" is worth a read, although not everything in there is fact:
    http://www.makeitfly.co.uk/Presentations/malloc1.pdf

BTW: FreeBSD 8.0 is going to be dedicated to the memory of John Birrell, 
who did the port; he passed away from a stroke on the 20th. At FUNIX 
Tuesday, we toasted to him and DTrace.

>
> It's thanksgiving here, but might get a chance to poke at it
> early next week.

No turkey for us Limeys for another month...

cheers,
BMS



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