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<p>Hi Simon,</p>
<p>skip to the list at the bottom for TL;DR<br>
</p>
<p>Every time I get an email about perf notes my heart sinks a
little. Hopefully there isn't a big issues here.</p>
<p>First of all, what commit is your branch based on? Have you
rebased on a recent master?<br>
</p>
<p>The output you posted says "<span lang="EN-US">...increased from
x86_64-linux-deb9 baseline @ HEAD~28". So this means it is using
metrics from CI as a baseline (that's the "</span><span
lang="EN-US"><span lang="EN-US">x86_64-linux-deb9" part), but
the baseline is from 28 commits ago (that's the "</span></span><span
lang="EN-US"><span lang="EN-US"><span lang="EN-US">HEAD~28"
part)</span>. 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:</span></span></p>
<p><span lang="EN-US"><span lang="EN-US"><br>
</span></span></p>
<p><span lang="EN-US"><span lang="EN-US">TL;DR</span></span></p>
<p><span lang="EN-US"><span lang="EN-US"><br>
</span></span></p>
<p><span lang="EN-US"><span lang="EN-US">1. Rebase of the latest
master</span></span></p>
<p><span lang="EN-US"><span lang="EN-US">2. Wait for CI to finish on
a more recent commit (see
<a class="moz-txt-link-freetext" href="https://gitlab.haskell.org/ghc/ghc/-/commits/master">https://gitlab.haskell.org/ghc/ghc/-/commits/master</a>)</span></span></p>
<p><span lang="EN-US"><span lang="EN-US">3.</span></span><span
lang="EN-US"> git fetch <a
href="https://gitlab.haskell.org/ghc/ghc-performance-notes.git">
https://gitlab.haskell.org/ghc/ghc-performance-notes.git</a></span><br>
</p>
<span lang="EN-US">refs/notes/perf:refs/notes/ci/perf</span>
<p><span lang="EN-US">4. Re run the tests</span></p>
<p><span lang="EN-US"><br>
</span></p>
<p><span lang="EN-US">Alternatively you can generate local metrics</span></p>
<p><span lang="EN-US"><br>
</span></p>
<p><span lang="EN-US">1. Checkout a recent commit to use as the
baseline (make sure the working tree is clean)</span></p>
<p><span lang="EN-US">2. Run the relevant perf tests</span></p>
<p><span lang="EN-US">3. Checkout your branches HEAD commit again</span></p>
<p><span lang="EN-US">4. Run the relevant tests again.</span></p>
<p><span lang="EN-US"><br>
</span></p>
<p><span lang="EN-US"><span lang="EN-US"></span></span></p>
<p><span lang="EN-US"><span lang="EN-US">If that doesn't do it, I
can have a closer look.</span></span></p>
<p><span lang="EN-US"><span lang="EN-US"><br>
</span></span></p>
<p><span lang="EN-US"><span lang="EN-US">David E<br>
</span></span></p>
<p><span lang="EN-US"><span lang="EN-US"><br>
</span></span></p>
<div class="moz-cite-prefix">On 6/26/20 11:29 AM, Simon Peyton Jones
via ghc-devs wrote:<br>
</div>
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<p class="MsoNormal"><span lang="EN-US">Despite a recent <o:p></o:p></span></p>
<p class="Code"><span lang="EN-US">git fetch <a
href="https://gitlab.haskell.org/ghc/ghc-performance-notes.git"
moz-do-not-send="true">
https://gitlab.haskell.org/ghc/ghc-performance-notes.git</a><o:p></o:p></span></p>
<p class="Code" style="text-indent:13.3pt"><span lang="EN-US">refs/notes/perf:refs/notes/ci/perf<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’m getting lots of perf
regressions in HEAD. For example<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US">=====> T9203(normal) 1 of
1 [0, 0, 0]<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US">]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<
<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US">cd "T9203.run" &&
./T9203 +RTS -V0 -tT9203.stats --machine-readable -RTS
<
<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US">runtime/bytes allocated
increased from x86_64-linux-deb9 baseline @ HEAD~28:<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US"> Expected T9203
(normal) runtime/bytes allocated: 56046952.0 +/-5%<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US"> Lower bound T9203
(normal) runtime/bytes allocated: 53244604
<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US"> Upper bound T9203
(normal) runtime/bytes allocated: 58849300
<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US"> Actual T9203
(normal) runtime/bytes allocated: 108464536
<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US"> Deviation T9203
(normal) runtime/bytes allocated: 93.5 %<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US">*** unexpected stat test
failure for T9203(normal)<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="Code"><span lang="EN-US">Performance Metrics (test
environment: local):<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="Code"><span lang="EN-US">T9203(normal)
runtime/bytes allocated 108464536.000<o:p></o:p></span></p>
<p class="Code"><span lang="EN-US">
(baseline @
HEAD~28) 56046952.000 [increased,
93.5%]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">What am I doing wrong?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Simon<o:p></o:p></span></p>
</div>
<br>
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<pre class="moz-signature" cols="72">--
David Eichmann, Haskell Consultant
Well-Typed LLP, <a class="moz-txt-link-freetext" href="http://www.well-typed.com">http://www.well-typed.com</a>
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