39 lines
1.1 KiB
Markdown
39 lines
1.1 KiB
Markdown
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# Benchmarking Build Performance of Android Clang
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Build performance is a vital metric as it affects development velocity, CI
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resource usage and the headroom for more sophisticated optimisation techniques.
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We heavily optimise Android Clang for peak performance.
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The Android Clang's compiler wrapper provides a convenient way to analyse the
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time spent building the Android platform. It can be produced by running:
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```
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rm -f /tmp/rusage.txt
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TOOLCHAIN_RUSAGE_OUTPUT=/tmp/rusage.txt m -j{processor count / 4}
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```
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We decrease the parallelism to reduce noise caused by resource contention. Also
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make sure RBE is off for the build. The resulting `rusage.txt` can be analysed
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with the following Python script:
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```
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#! /usr/bin/env python3
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import json
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import sys
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total_clang_time = 0
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total_clang_tidy_time = 0
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with open(sys.argv[1], 'r') as rusage:
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for line in rusage:
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data = json.loads(line)
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if 'clang-tidy' in data['compiler']:
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total_clang_tidy_time += data['elapsed_real_time']
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else:
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total_clang_time += data['elapsed_real_time']
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print('Total clang time', total_clang_time)
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print('Total clang-tidy time', total_clang_tidy_time)
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```
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