Also looking at gitlab CI, there are a lot of recent commits on master without completed CI runs I thought that wasn't possible. Isn't that what CI is *for*? And in any case, I don't think anyone will have accepted a doubling of bytes-allocated on T9803, in the last 28 commits, without lots of song and dance. Ben do you know what is going on? Simon From: ghc-devs On Behalf Of David Eichmann Sent: 26 June 2020 12:06 To: ghc-devs@haskell.org Subject: Re: Perf notes Hi Simon, skip to the list at the bottom for TL;DR Every time I get an email about perf notes my heart sinks a little. Hopefully there isn't a big issues here. First of all, what commit is your branch based on? Have you rebased on a recent master? The output you posted says "...increased from x86_64-linux-deb9 baseline @ HEAD~28". So this means it is using metrics from CI as a baseline (that's the "x86_64-linux-deb9" part), but the baseline is from 28 commits ago (that's the "HEAD~28" part). The baseline seems a bit old. Also looking at gitlab CI, there are a lot of recent commits on master without completed CI runs. So this might be a matter of waiting for CI to finish, then fetching the CI metrics again. Any way this may help: TL;DR 1. Rebase of the latest master 2. Wait for CI to finish on a more recent commit (see https://gitlab.haskell.org/ghc/ghc/-/commits/masterhttps://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fcommits%2Fmaster&data=02%7C01%7Csimonpj%40microsoft.com%7Cc46e95a2b82c42ce4c1608d819c10ecd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637287664255730878&sdata=7wmJDbNNCoRb3ooWXEcxmzOqkNch4kuVNHyAQhhn0Ko%3D&reserved=0) 3. git fetch https://gitlab.haskell.org/ghc/ghc-performance-notes.githttps://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc-performance-notes.git&data=02%7C01%7Csimonpj%40microsoft.com%7Cc46e95a2b82c42ce4c1608d819c10ecd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637287664255730878&sdata=7gipL1xRcNrHR1%2BxWZt9aS7L%2F0KzHgU31InvZk%2FRvnM%3D&reserved=0 refs/notes/perf:refs/notes/ci/perf 4. Re run the tests Alternatively you can generate local metrics 1. Checkout a recent commit to use as the baseline (make sure the working tree is clean) 2. Run the relevant perf tests 3. Checkout your branches HEAD commit again 4. Run the relevant tests again. If that doesn't do it, I can have a closer look. David E On 6/26/20 11:29 AM, Simon Peyton Jones via ghc-devs wrote: Despite a recent git fetch https://gitlab.haskell.org/ghc/ghc-performance-notes.githttps://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc-performance-notes.git&data=02%7C01%7Csimonpj%40microsoft.com%7Cc46e95a2b82c42ce4c1608d819c10ecd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637287664255740875&sdata=aY3P2tJBpL3Ut8RdubHZka0hFtlnr2yhEuNSYA5OfLI%3D&reserved=0 refs/notes/perf:refs/notes/ci/perf I'm getting lots of perf regressions in HEAD. For example =====> T9203(normal) 1 of 1 [0, 0, 0] ]0;T9203(normal) 1 of 1 [0, 0, 0]cd "T9203.run" && "/home/simonpj/code/HEAD-3/inplace/bin/ghc-stage2" -o T9203 T9203.hs -dcore-lint -dstg-lint -dcmm-lint -no-user-package-db -rtsopts -fno-warn-missed-specialisations -fshow-warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -Werror=compat -dno-debug-output -O2< cd "T9203.run" && ./T9203 +RTS -V0 -tT9203.stats --machine-readable -RTS < runtime/bytes allocated increased from x86_64-linux-deb9 baseline @ HEAD~28: Expected T9203 (normal) runtime/bytes allocated: 56046952.0 +/-5% Lower bound T9203 (normal) runtime/bytes allocated: 53244604 Upper bound T9203 (normal) runtime/bytes allocated: 58849300 Actual T9203 (normal) runtime/bytes allocated: 108464536 Deviation T9203 (normal) runtime/bytes allocated: 93.5 % *** unexpected stat test failure for T9203(normal) Performance Metrics (test environment: local): T9203(normal) runtime/bytes allocated 108464536.000 (baseline @ HEAD~28) 56046952.000 [increased, 93.5%] What am I doing wrong? Simon _______________________________________________ ghc-devs mailing list ghc-devs@haskell.orgmailto:ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devshttps://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.haskell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc-devs&data=02%7C01%7Csimonpj%40microsoft.com%7Cc46e95a2b82c42ce4c1608d819c10ecd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637287664255740875&sdata=7qu5Ji4KN61LG8RP1X7%2B3GG2kq%2FfSUbnthjV33sYubs%3D&reserved=0 -- David Eichmann, Haskell Consultant Well-Typed LLP, http://www.well-typed.comhttps://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.well-typed.com%2F&data=02%7C01%7Csimonpj%40microsoft.com%7Cc46e95a2b82c42ce4c1608d819c10ecd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637287664255750861&sdata=VL3fotTvZCGb0wVbrlzmIGHkGEYyqPAlN%2BWd5RRXEN0%3D&reserved=0 Registered in England & Wales, OC335890 118 Wymering Mansions, Wymering Road, London W9 2NF, England

Re the doubling of bytes-allocated on T9803, that's a good point. Due to the recent change in RSA keys, CI is recently failing to upload metrics (e.g. [1])! I'll fix that then see if I can track down where / if the metric has really regressed in master. Thanks Yes we run CI on MRs, but once merged into master CI is run again. It's only those metrics from CI on master (post merge) that are ultimately uploaded / used as a baseline. OK. But they are guaranteed to be 100.0% identical to the ones discovered by CI, aren't they? So it's just an implementation detail whether the numbers you save are gotten from one run, or another identical one. I'm still lost about when I can rely on the perf output of CI and when I can't. I'm really hoping for a simple answer like: * The CI log tells you the comparison between the preceding commit and this one No ifs, no buts. Simple! Incidentally, would it be possible to output a table (in the log) like we get from nofib-analyse. It looks like this Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- boyer -0.3% +5.4% +0.7% +1.0% 0.0% cichelli -0.3% +5.9% -9.9% -9.5% 0.0% compress2 -0.4% +9.6% +7.2% +6.4% 0.0% constraints -0.3% +0.2% -3.0% -3.4% 0.0% cryptarithm2 -0.3% -3.9% -2.2% -2.4% 0.0% gamteb -0.4% +2.5% +2.8% +2.8% 0.0% life -0.3% -2.2% -4.7% -4.9% 0.0% lift -0.3% -0.3% -0.8% -0.5% 0.0% linear -0.3% -0.1% -4.1% -4.5% 0.0% mate -0.2% +1.4% -2.2% -1.9% -14.3% parser -0.3% -2.1% -5.4% -4.6% 0.0% puzzle -0.3% +2.1% -6.6% -6.3% 0.0% simple -0.4% +2.8% -3.4% -3.3% -2.2% veritas -0.1% +0.7% -0.6% -1.1% 0.0% wheel-sieve2 -0.3% -19.2% -24.9% -24.5% -42.9% -------------------------------------------------------------------------------- Min -0.4% -19.2% -24.9% -24.5% -42.9% Max +0.1% +9.6% +7.2% +6.4% +33.3% Geometric Mean -0.3% -0.0% -3.0% -2.9% -0.3% Instantly comprehensible, one line per benchmark. I find I spent quite a lot of time search manually in the log and manually building a table (or excerpts thereof) looking like this. I don't have an opinion about the columns, just wanting a table with one line per benchmark, and a number of columns. Thanks Simon From: David Eichmann Sent: 27 June 2020 20:39 To: Simon Peyton Jones ; ghc-devs@haskell.org Subject: Re: Perf notes

I thought that wasn't possible. Isn't that what CI is *for*?

Yes we run CI on MRs, but once merged into master CI is run again. It's only those metrics from CI on master (post merge) that are ultimately uploaded / used as a baseline. Re the doubling of bytes-allocated on T9803, that's a good point. Due to the recent change in RSA keys, CI is recently failing to upload metrics (e.g. [1])! I'll fix that then see if I can track down where / if the metric has really regressed in master. [1] "fatal: Could not read from remote repository." https://gitlab.haskell.org/ghc/ghc/-/jobs/378487https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fjobs%2F378487&data=02%7C01%7Csimonpj%40microsoft.com%7C7e93b1bdba414d2b98ae08d81ad1b2e6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637288835244421907&sdata=6SpTm36gxWqp0bPp78Kz037d%2BykCs2g%2F0GGZnwXyKMs%3D&reserved=0 -- David Eichmann, Haskell Consultant Well-Typed LLP, http://www.well-typed.comhttps://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.well-typed.com%2F&data=02%7C01%7Csimonpj%40microsoft.com%7C7e93b1bdba414d2b98ae08d81ad1b2e6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637288835244431897&sdata=9%2BIEhlNYjNsc%2FopbyMryXa7dG40d79JrWeQVqtZtx8g%3D&reserved=0 Registered in England & Wales, OC335890 118 Wymering Mansions, Wymering Road, London W9 2NF, England

Simon, you are on windows, correct? If so the result you posted is using the "x86_64-linux-deb9" environment as a baseline when it should be using "x86_64" which is much closer to the result you're getting. WSL actually. (Windows Subsystem for Linux.) Simon From: David Eichmann Sent: 02 July 2020 16:25 To: Simon Peyton Jones ; ghc-devs@haskell.org Subject: Re: Perf notes Hello, So CI metrics are being pushed again, good. The immediate issue was perf test T9803. I've looked at metrics across all CI test environments and the last 300 commit on master. Metric looks stable. I've attached the output of: `python3 ./testsuite/driver/perf_notes.py --chart T9203.html --ci --test-name T9203 origin/master~300..origin/master`. Simon, you are on windows, correct? If so the result you posted is using the "x86_64-linux-deb9" environment as a baseline when it should be using "x86_64" which is much closer to the result you're getting.

So it's just an implementation detail whether the numbers you save are gotten from one run, or another identical one.

For the most part yes, but since we usually rebase and batch commit with marge bot, we are really creating a new commit. So it makes some sense to rerun CI.

The CI log tells you the comparison between the preceding commit and this one

I'd love for this to be the behavior too. The problem is, most of the time we don't have the metrics for the parent commit, and generating them is expensive. We could automatically checkout / build the previous commit and run perf tests, but this doesn't seem like good design. That's why we've resorted to searching for "most recent" local or CI metrics to establish an approximate baseline. Requiring the developers to always run perf tests locally on the previous commit will be extremely annoying. Another option is to just disable perf tests by default. It's not satisfying but it's hard to think of a better solution. I think the current implementation is still more convenient than before, where baselines were just hard coded into test files. If you wanted to investigate a particular commit, you had to manually establish a baseline. Perhaps the problem with this new system is that it's a bit too "magical" and it's unclear how to interpret results. Perhaps this can be remedied with better output form the test runner.

Would it be possible to output a table (in the log) like we get from nofib-analyse

Absolutely. This should be fairly easy to implement. I've created #18417. - David E On 6/29/20 3:08 PM, Simon Peyton Jones wrote: Re the doubling of bytes-allocated on T9803, that's a good point. Due to the recent change in RSA keys, CI is recently failing to upload metrics (e.g. [1])! I'll fix that then see if I can track down where / if the metric has really regressed in master. Thanks Yes we run CI on MRs, but once merged into master CI is run again. It's only those metrics from CI on master (post merge) that are ultimately uploaded / used as a baseline. OK. But they are guaranteed to be 100.0% identical to the ones discovered by CI, aren't they? So it's just an implementation detail whether the numbers you save are gotten from one run, or another identical one. I'm still lost about when I can rely on the perf output of CI and when I can't. I'm really hoping for a simple answer like: * The CI log tells you the comparison between the preceding commit and this one No ifs, no buts. Simple! Incidentally, would it be possible to output a table (in the log) like we get from nofib-analyse. It looks like this Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- boyer -0.3% +5.4% +0.7% +1.0% 0.0% cichelli -0.3% +5.9% -9.9% -9.5% 0.0% compress2 -0.4% +9.6% +7.2% +6.4% 0.0% constraints -0.3% +0.2% -3.0% -3.4% 0.0% cryptarithm2 -0.3% -3.9% -2.2% -2.4% 0.0% gamteb -0.4% +2.5% +2.8% +2.8% 0.0% life -0.3% -2.2% -4.7% -4.9% 0.0% lift -0.3% -0.3% -0.8% -0.5% 0.0% linear -0.3% -0.1% -4.1% -4.5% 0.0% mate -0.2% +1.4% -2.2% -1.9% -14.3% parser -0.3% -2.1% -5.4% -4.6% 0.0% puzzle -0.3% +2.1% -6.6% -6.3% 0.0% simple -0.4% +2.8% -3.4% -3.3% -2.2% veritas -0.1% +0.7% -0.6% -1.1% 0.0% wheel-sieve2 -0.3% -19.2% -24.9% -24.5% -42.9% -------------------------------------------------------------------------------- Min -0.4% -19.2% -24.9% -24.5% -42.9% Max +0.1% +9.6% +7.2% +6.4% +33.3% Geometric Mean -0.3% -0.0% -3.0% -2.9% -0.3% Instantly comprehensible, one line per benchmark. I find I spent quite a lot of time search manually in the log and manually building a table (or excerpts thereof) looking like this. I don't have an opinion about the columns, just wanting a table with one line per benchmark, and a number of columns. Thanks Simon From: David Eichmann mailto:davide@well-typed.com Sent: 27 June 2020 20:39 To: Simon Peyton Jones mailto:simonpj@microsoft.com; ghc-devs@haskell.orgmailto:ghc-devs@haskell.org Subject: Re: Perf notes

I thought that wasn't possible. Isn't that what CI is *for*?

Yes we run CI on MRs, but once merged into master CI is run again. It's only those metrics from CI on master (post merge) that are ultimately uploaded / used as a baseline. Re the doubling of bytes-allocated on T9803, that's a good point. Due to the recent change in RSA keys, CI is recently failing to upload metrics (e.g. [1])! I'll fix that then see if I can track down where / if the metric has really regressed in master. [1] "fatal: Could not read from remote repository." https://gitlab.haskell.org/ghc/ghc/-/jobs/378487https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fjobs%2F378487&data=02%7C01%7Csimonpj%40microsoft.com%7Cc4f75c38623e40b4983608d81e9c118a%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637293004078959683&sdata=1obE6D2oHoZxYizjzOAsxqOcW%2B3PcY6kqfckNgKFFQg%3D&reserved=0 -- David Eichmann, Haskell Consultant Well-Typed LLP, http://www.well-typed.comhttps://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.well-typed.com%2F&data=02%7C01%7Csimonpj%40microsoft.com%7Cc4f75c38623e40b4983608d81e9c118a%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637293004078969677&sdata=lk2tF4MQQwKPoMO2ABXuWXI871hTlPNXb0O5YICa5Bg%3D&reserved=0 Registered in England & Wales, OC335890 118 Wymering Mansions, Wymering Road, London W9 2NF, England -- David Eichmann, Haskell Consultant Well-Typed LLP, http://www.well-typed.comhttps://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.well-typed.com%2F&data=02%7C01%7Csimonpj%40microsoft.com%7Cc4f75c38623e40b4983608d81e9c118a%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637293004078969677&sdata=lk2tF4MQQwKPoMO2ABXuWXI871hTlPNXb0O5YICa5Bg%3D&reserved=0 Registered in England & Wales, OC335890 118 Wymering Mansions, Wymering Road, London W9 2NF, England