[llvm-dev] Buildbots timing out on full builds

Vitaly Buka via llvm-dev llvm-dev at lists.llvm.org
Wed May 31 14:52:02 PDT 2017


Is https://reviews.llvm.org/differential/diff/100829/  replacement for
r303341?

If so LGTM.

r303542 msan  AArch64InstructionSelector.cpp: 1m17.209s
r303542+diff/100829/ <https://reviews.llvm.org/differential/diff/100829/>
msan  AArch64InstructionSelector.cpp:  1m24.724s




On Wed, May 31, 2017 at 6:13 AM, Daniel Sanders <daniel_l_sanders at apple.com>
wrote:

> Great! I expect I'll be able to cut it down further once I start fusing
> these smaller state-machines together. Before that, I'll re-order the
> patches that went into that diff so that I don't have to re-commit the
> regression before fixing it.
>
> On 31 May 2017, at 13:48, Diana Picus <diana.picus at linaro.org> wrote:
>
> Hi,
>
> This runs in:
> real    13m6.296s
> user    42m45.191s
> sys     1m2.030s
>
> (on top of a fully built r303542). It should be fine for the ARM bots.
>
> However, you need to 'return std::move(M)' at line 1884.
>
> @Vitaly, is it ok for your bots as well?
>
> Cheers,
> Diana
>
> On 31 May 2017 at 10:21, Daniel Sanders <daniel_l_sanders at apple.com>
> wrote:
>
>> Hi Diana and Vitaly,
>>
>> Could you give https://reviews.llvm.org/differential/diff/100829/ a try?
>> When measuring the compile of AArch64InstructionSelector.cpp.o with asan
>> enabled and running under instruments's Allocation profiler, my machine
>> reports that the cumulative memory allocations is down to ~3.5GB (was
>> ~10GB), the number of allocations down to ~4 million (was ~23 million), and
>> the compile time down to ~15s (was ~60s).
>>
>> The patch is based on r303542 and the main change is that most of the
>> generated C++ has been replaced with a state-machine based implementation.
>> It's not fully converted to a state-machine yet since it generates lots of
>> smaller machines (one matcher and one emitter per rule) instead of a single
>> machine but it's hopefully sufficient to unblock my patch series.
>>
>> On 26 May 2017, at 09:10, Diana Picus <diana.picus at linaro.org> wrote:
>>
>> Ok, that sounds reasonable. I'm happy to test more patches for you
>> when they're ready.
>>
>> On 25 May 2017 at 17:39, Daniel Sanders <daniel_l_sanders at apple.com>
>> wrote:
>>
>> Thanks for trying that patch. I agree that 34 mins still isn't good
>> enough but we're heading in the right direction.
>>
>> Changing the partitioning predicate to the instruction opcode rather than
>> the number of operands in the top-level instruction will hopefully cut it
>> down further. I also have a patch that shaves a small amount off of the
>> compile-time by replacing the various LLT::scalar()/LLT::vector() calls
>> with references to LLT objects that were created in advance. I tried
>> something similar with the getRegBankForRegClass() but I haven't written
>> that as a patch yet since that one requires some refactors to get access to
>> a mapping that RegisterBankEmitter.cpp knows. In my experiment I edited
>> this information into AArchGenGlobalISel.inc by hand.
>>
>> I think the real solution is to convert the generated C++ to the
>> state-machine that we intended to end up with. I don't think we'll be able
>> to put it off much longer given that we're hitting compile-time problems
>> when we can only import 25% of the rules. That said, I have a couple more
>> nearly-finished patches I'd like to get in before we introduce the state
>> machine. Hopefully, the above tricks will be enough to save me a re-write.
>>
>> On 25 May 2017, at 16:11, Diana Picus <diana.picus at linaro.org> wrote:
>>
>> Hi Daniel,
>>
>> I built r303542, then applied your patch and built again and it still
>> takes
>> real    34m30.279s
>> user    84m36.553s
>> sys     0m58.372s
>>
>> This is better than the 50m I saw before, but I think we should try to
>> make it a bit faster. Do you have any other ideas to make it work?
>>
>> Thanks,
>> Diana
>>
>>
>> On 22 May 2017 at 11:22, Diana Picus <diana.picus at linaro.org> wrote:
>>
>> Hi Daniel,
>>
>> I did your experiment on a TK1 machine (same as the bots) and for r303258
>> I get:
>> real    18m28.882s
>> user    35m37.091s
>> sys     0m44.726s
>>
>> and for r303259:
>> real    50m52.048s
>> user    88m25.473s
>> sys     0m46.548s
>>
>> If I can help investigate, please let me know, otherwise we can just
>> try your fixes and see how they affect compilation time.
>>
>> Thanks,
>> Diana
>>
>> On 22 May 2017 at 10:49, Daniel Sanders <daniel_l_sanders at apple.com>
>> wrote:
>>
>> 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> 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>
>> wrote:
>>
>>
>> On 19 May 2017, at 14:54, Daniel Sanders via llvm-dev
>> <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> 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
>> r303346:
>> 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
>> r303259:
>> 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
>>
>> 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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