Re: LuaJIT 2.1 Profiler released
- From: Mike Pall <mike-1310@xxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Mon, 14 Oct 2013 19:57:04 +0200
Luke Gorrie wrote:
> In that case, I suppose there's no real chance for line-based profiling,
> since Instruction Pointer won't correlate well with the specific event of
> interest.
I wouldn't discount this so quickly. Sampling-based profilers are
not based on direct correlation, yet they still come up with
useful results. Instead of count++ to measure CPU time one does
count += nevents.
> btw is cachegrind usable with LuaJIT, either in practice or in principle?
Only in principle. Apart from being rather slow it's kind of hard
to interpret its results for JIT-compiled code. And its cost model
for e.g. branch prediction is probably insufficient to model the
actual costs on a modern x86 CPU.
--Mike
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