[PATCH] [RFC] malloc: Reduce worst-case behaviour with madvise and refault overhead

[Rich Felker]

On Wed, Feb 11, 2015 at 02:19:26PM +0000, Mel Gorman wrote:
> > > In the cases where I've seen this happen
> > > on other workloads (firefix, evolution, mariadb during database init from
> > > system) the cost of the operations on the buffer dominated. The malloc/free
> > > cost was there but the performance difference is in the noise.
> > 
> > If it's not distinguishable from noise in actual usage cases, then I'm
> > skeptical that there's a need to fix this issue.
> > 
> 
> I take that is a NAK for v1 of the patch. How about V2? It is expected
> that heap trims can be controlled with tuning parameters but right now,
> it's not possible to tune the trim threshold for per-thread heaps. V2 of
> the patch fixes that and at least is consistent behaviour.

I don't think I'm qualified to discuss specific code changes to
glibc's allocator. I'll leave this to others who know it better. I was
just weighing in on the high-level aspects of the proposed changes
which made sense to discuss without knowledge specific to glibc's
malloc internals.

Rich