[llvm-dev] Noisy benchmark results?

Mikael Holmén via llvm-dev llvm-dev at lists.llvm.org
Mon Feb 27 00:46:54 PST 2017


I'm trying to run the benchmark suite:

I'm doing it the lnt way, as described at:

I don't know what to expect but the results seems to be quite noisy and 
unstable. E.g I've done two runs on two different commits that only 
differ by a space in CODE_OWNERS.txt on my 12 core ubuntu 14.04 machine 

  lnt runtest nt --sandbox SANDBOX --cc <path-to-my-clang> --test-suite 
/data/repo/test-suite -j 8

And then I get the following top execution time regressions:

The numbers bounce around a lot if I do more runs.

Given the amount of noise I see here I don't know to sort out 
significant regressions if I actually do a real change in the compiler.

Are the above results expected?

How to use this?

As a bonus question, if I instead run the benchmarks with an added -m32:
  lnt runtest nt --sandbox SANDBOX --cflag=-m32 --cc <path-to-my-clang> 
--test-suite /data/repo/test-suite -j 8

I get three failures:

--- Tested: 2465 tests --
FAIL: MultiSource/Applications/ClamAV/clamscan.compile_time (1 of 2465)
FAIL: MultiSource/Applications/ClamAV/clamscan.execution_time (494 of 2465)
(495 of 2465)

Is this known/expected or do I do something stupid?


More information about the llvm-dev mailing list