[llvm-dev] Performance metrics with LLVM

Tobias Grosser via llvm-dev llvm-dev at lists.llvm.org
Tue Jul 4 02:02:55 PDT 2017

On Tue, Jul 4, 2017, at 09:48 AM, Kristof Beyls wrote:
> Hi Tobias,
> The metrics that you can collect in LNT are fixed per "test suite".
> There are 2 such "test suite"s defined in LNT at the moment: nts and
> compile.
> For more details on this, see
> http://llvm.org/docs/lnt/concepts.html#test-suites.
> AFAIK, If you need to collect different metrics, you'll need to define a
> new "test suite". I'm afraid I don't really know what is needed for that.
> I'm guessing you may need to write some LNT code to do so, but I'm not
> sure. Hopefully Matthias or Chris will be able to explain how to do that.
> We probably should investigate how to make it easier to define new
> "test-suite"s more easily. Or at least make it easier to record different
> sets of metrics more easily, without having to change the LNT code or a
> running LNT server instance.
> The question on recording a different set of metrics has come up on this
> list before, so it seems like it's an issue people do run into from time
> to time.

Hi Kristof,

thanks for your fast reply. This is a very helpful summary that confirms
my current understanding in parts. I never run the "compile" test suite,
so I am not sure how much of the statistics interface is used by it (if
at all). I somehow had the feeling something else might exist, as the
cmake test-suite
runner dumps some of the statistics to stdout. Would be interested to
read if Chris or Matthias have more insights.

> Thanks,
> Kristof
> On 4 Jul 2017, at 08:27, Tobias Grosser
> <tobias.grosser at inf.ethz.ch<mailto:tobias.grosser at inf.ethz.ch>> wrote:
> Dear all,
> I wanted to gather LLVM statistics with lnt and found a nice flag, but
> am unsure how such statistics can be made available in the LNT web
> interface.
> which allows me to gather all the LLVM "-stats" output. On top of this I
> see that the LNT cmake test-suite also dumps code-size statistics when
> running, that look as follows:
> size: 10848
> size..bss: 48
> size..comment: 218
> size..ctors: 16
> size..data: 4
> size..dtors: 16
> size..dynamic: 416
> size..dynsym: 168
> size..eh_frame: 172
> size..eh_frame_hdr: 44
> I can find all these statistics in a file called:
> /scratch/leone/grosser/base/sandbox/test-2017-07-04_06-14-43/outputTd2xPU.json
> but they do not appear in:
> /scratch/leone/grosser/base/sandbox/test-2017-07-04_06-14-43/report.json
> and in fact do not seem to be submitted to the LNT server.
> Matthias added support for TEST_SUITE_COLLECT_STATS a while ago, but I
> am unsure how it is expected to be used. A google search did not find
> any relevant documentation. Is anybody using this feature today?
> Best,
> Tobias

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