[Haskell-cafe] Cache miss performance costs for Haskell programs?
mail at joachim-breitner.de
Wed Aug 31 02:52:03 UTC 2016
Am Dienstag, den 30.08.2016, 16:57 +0100 schrieb Rob Stewart:
> Thanks for the reply, and really interesting work!
> > In the following measurements, I avoid this problem by not
> > measuring program execution time, but simply by counting the number
> > of instructions performed.
> Are these a count of all instructions performed at runtime? Did you
> isolate a count of just the memory access instructions that ended up
> fetching from main memory? Also, did you measure the clock cycle
> latency averages for memory access instructions for (B) (C) and (D),
> to get an indication of cache misses?
I did not dig deeper. I just ran the test suite under valgrind (nofib
has support for that) and took the number of instructions that came
out. My working hypothesis was that the effect of high level (i.e.
Core) transformation on code layout / branch prediction / pipeline
stuff / cache hits and misses are too hard to predict and such
measurements would not give me useful information.
But you seem to be after a more optimistic and principled approach
here, so I’ll be keen to hear what you find out.
Joachim “nomeata” Breitner
mail at joachim-breitner.de • https://www.joachim-breitner.de/
XMPP: nomeata at joachim-breitner.de • OpenPGP-Key: 0xF0FBF51F
Debian Developer: nomeata at debian.org
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