Re: better malloc strategies

[Howard Chu <hyc@symas.com>]

David Boreham wrote:
> Howard Chu wrote:
>
> > What's also interesting is that for Hoard, Umem, and Tcmalloc, the 
> > multi-threaded query times are consistently about 2x slower than the 
> > single-threaded case. The 2x slowdown makes sense since it's only a 
> > dual-core CPU and it's doing 4x as much work. This kinda says that the 
> > cost of malloc is overshadowed by the overhead of thread scheduling.
>
> Is it possible that the block stride in the addresses returned by 
> malloc() is affecting
> cache performance in the glibc case ?
> If they are too close I think it is possible to thrash cache lines 
> between cores.

That's a very good question, and I don't have an answer yet. I've been 
working on some threading extensions for cachegrind so I can investigate 
that. Unfortunately its existing infrastructure doesn't lend itself well 
to tracking multiple caches, so that's been slow going.

--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc
  OpenLDAP Core Team            http://www.openldap.org/project/