libgcj and the NPTL posix threads implementation

Boehm, Hans
Mon Mar 1 22:28:00 GMT 2004

I'm surprised that pthread mutexes are that significant.  That may suggest a
configuration problem. 

The collector does use pthread mutexes in the gcj configuration.  But that's because
thread-local allocation is enabled, and the small object allocations should not
normally involve locking. 

Is this a benchmark that allocates primarily larger objects?  The maximum size
for thread-local allocation is fairly small (512bytes?).  Or are you creating
lots of short-lived threads?


> -----Original Message-----
> From: Anthony Green []
> Sent: Friday, February 27, 2004 12:18 PM
> To: Boehm, Hans
> Cc: 'Michael Koch';
> Subject: RE: libgcj and the NPTL posix threads implementation
> On Fri, 2004-02-27 at 10:15, Boehm, Hans wrote:
> > You might try .  
> I'm biased,
> > but a design goal was to build a quick-and-dirty profiler 
> that's trivial
> > to install and run. 
> Just tried it, and it's pretty neat.
> pthread mutexes do show up in my benchmark at about 15% of the time. 
> They are used extensively by the GC.   Perhaps we could your light
> weight locks here as well.
> AG
> -- 
> Anthony Green <>
> Red Hat, Inc.

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