[llvm-dev] Buildbots timing out on full builds

Mon May 22 01:49:06 PDT 2017

r303341 is the re-commit of the r303259 which tripled the number of rules that can be imported into GlobalISel from SelectionDAG. A compile time regression is to be expected but when I looked into it I found it was ~25s on my machine for the whole incremental build rather than the ~12mins you are seeing. I'll take another look.

I'm aware of a couple easy improvements we could make to the way the importer works. I was leaving them until we change it over to a state machine but the most obvious is to group rules by their top-level gMIR instruction. This would reduce the cost of the std::sort that handles the rule priorities in generating the source file and will also make it simpler for the compiler to compile it.

> On 21 May 2017, at 11:16, Vitaly Buka <vitalybuka at google.com> wrote:
> 
> It must be r303341, I commented on corresponding llvm-commits thread.
> 
> On Fri, May 19, 2017 at 7:34 AM, Diana Picus via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> Ok, thanks. I'll try to do a bisect next week to see if I can find it.
> 
> Cheers,
> Diana
> 
> On 19 May 2017 at 16:29, Daniel Sanders <daniel_l_sanders at apple.com <mailto:daniel_l_sanders at apple.com>> wrote:
> >
> >> On 19 May 2017, at 14:54, Daniel Sanders via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> >>
> >> r303259 will have increased compile-time since it tripled the number of importable
> >> SelectionDAG rules but a quick measurement building the affected file:
> >>    ninja lib/Target/<Target>/CMakeFiles/LLVM<Target>CodeGen.dir/<Target>InstructionSelector.cpp.o
> >> for both ARM and AArch64 didn't show a significant increase. I'll check whether
> >> it made a different to linking.
> >
> > I don't think it's r303259. Starting with a fully built r303259, then updating to r303258 and running 'ninja' gives me:
> >         real    2m28.273s
> >         user    13m23.171s
> >         sys     0m47.725s
> > then updating to r303259 and running 'ninja' again gives me:
> >         real    2m19.052s
> >         user    13m38.802s
> >         sys     0m44.551s
> >
> >> sanitizer-x86_64-linux-fast also timed out after one of my commits this morning.
> >>
> >>> On 19 May 2017, at 14:14, Diana Picus <diana.picus at linaro.org <mailto:diana.picus at linaro.org>> wrote:
> >>>
> >>> Hi,
> >>>
> >>> We've noticed that recently some of our bots (mostly
> >>> clang-cmake-armv7-a15 and clang-cmake-thumbv7-a15) started timing out
> >>> whenever someone commits a change to TableGen:
> >>>
> >>> r303418: http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7268 <http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7268>
> >>> r303346: http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7242 <http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7242>
> >>> r303341: http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7239 <http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7239>
> >>> r303259: http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7198 <http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7198>
> >>>
> >>> TableGen changes before that (I checked about 3-4 of them) don't have
> >>> this problem:
> >>> r303253: http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7197 <http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/7197>
> >>>
> >>> That one in particular actually finishes the whole build in 635s,
> >>> which is only a bit over 50% of the timeout limit (1200s). So, between
> >>> r303253 and now, something happened that made full builds
> >>> significantly slower. Does anyone have any idea what that might have
> >>> been? Also, has anyone noticed this on other bots?
> >>>
> >>> Thanks,
> >>> Diana
> >>
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> >
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