Re: cpuset/affinity interfaces and TSX lock elision in musl

[Rob Landley <rob@landley.net>]

On 05/17/2013 12:29:03 PM, Rich Felker wrote:
> > locks should not be the bottleneck in applications
> > unless there is too much shared state on hot paths,
> > which is probably a design bug or a special use-case
> > for which non-standard synchronization methods may
> > be better anyway
> 
> One place where there is unfortunately a huge amount of shared state
> is memory management; this is inevitable. Even if we don't use lock
> elision for pthread locks, it might be worth considering using it
> _internally_ in malloc when it's available. It's hard to say without
> any measurements, but this might result in a malloc that beats
> ptmalloc, etc. without any thread-locale management.

I thought the point of futexes was that in the non-contention case you  
don't enter the kernel at all?

I really don't see how lock elision is supposed to improve upon that.  
If you're optimizing the contended case, something is wrong.

Rob