Messages in this thread | | | Date | Mon, 11 Nov 2013 22:09:24 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] mm: cache largest vma |
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* Davidlohr Bueso <davidlohr@hp.com> wrote:
> > Or is access to varied in the Oracle case that it's missing the cache > > all the time, because the rbtree causes many cachemisses as the > > separate nodes are accessed during an rb-walk? > > Similar to get_cycles(), is there anyway to quickly measure the amount > of executed instructions? Getting the IPC for the mmap_cache (this of > course is constant) and the treewalk could give us a nice overview of > the function's cost. I was thinking of stealing some perf-stat > functionality for this but didn't get around to it. Hopefully there's an > easier way...
There's no such easy method I'm afraid (Frederic's probe based trigger facility will give us that and more - but it's not ready yet) - but you could try profiling the workload for significant cache-misses:
perf record -e cache-misses ...
I _think_ if it's really catastrophic cache-misses then the rbtree walk should light up on the perf radar like crazy.
Thanks,
Ingo
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