[llvm-dev] LLD benchmark results for all commits

[Rui Ueyama via llvm-dev]

Because the graph hides some part of the table?

On Fri, Jan 15, 2016 at 2:54 PM, David Blaikie <dblaikie at gmail.com> wrote:

> Cool - thanks for sharing!
>
> Perhaps you could add a graph of the times in another sheet/beside the
> table?
>
> On Fri, Jan 15, 2016 at 2:42 PM, Rui Ueyama via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Speed is one of the most important goals for the new ELF linker. I ran a
>> benchmark for every commit to LLD/ELF that was made after the last October,
>> and I'd like to share the result. The motivation is to see if the linker is
>> getting slower as we add more features, and if so, which commits are heavy
>> ones in terms of performance. I measured time to link the same Clang
>> executable.
>>
>> Here is the result. This table contains a commit message, a SVN revision
>> number, time to link, size of the resulting Clang binary in each row.
>>
>>
>> https://docs.google.com/spreadsheets/d/1QlQZ51VQUna6gX0qXj19v_ZEII5vGaHrUhBKq-Z_9uc/edit?usp=sharing
>>
>> As you can see, the linker is faster than the original. A few key
>> findings are listed below:
>>
>>  - The linker tend to be gradually getting slower over time in general.
>>  - There are a few commits that increased link time by a few percent or
>> more.
>>  - However, we also committed a few performance improvement changes to
>> offset them.
>>
>> The commit that increased link time most (+15%) is r251212: Add support
>> for merging string from SHF_STRINGS sections. This does not come as a
>> surprise since string merging is a computationally heavy operation.
>>
>> The commit that decreased link time most (-29%) is r250315: ELF2: Merge
>> .{text,rodata,data,bss}.* sections. This is because the commit
>> significantly decreased number of sections in the output.
>>
>> The following commits are also noteworthy.
>>
>>  - r257017: ELF: Improve performance of string table construction
>> (-14.0%)
>>  - r251332: Optimize StringTableBuilder (-7.8%)
>>
>> Ideally, we should have a perf bot to run a benchmark for every commit,
>> so that we do not accidentally commit changes that hurt performance.
>>
>> Overall, I'm satisfied with the result. It found no commit that
>> increases link time for no justifiable reason.
>>
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>>
>>
>
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