Local Windows Clang builds are 60% slower than VC |
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Issue descriptionI have been doing local builds because I'm trying to avoid the linking slowness with goma. I couldn't believe how slow it was so I benchmarked Clang vs VC on my Z840. GN args: target_cpu = "x86" is_clang = ... enable_nacl = false Command line: gn clean out/eraseme ninja -C out/eraseme chrome For this: MSVC: 50:51 Clang: 74:30
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Oct 16 2017
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Oct 16 2017
This is known. Both with goma and with jumbo builds, the difference is much smaller, so we'll focus on this after the switch. (There's a doc somewhere, both on prioritization and on speedup opportunities)
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Nov 22 2017
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Nov 22 2017
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Nov 22 2017
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Feb 28 2018
We've had two threads so far where clang-cl was much slower for folks due to Windows Defender (one on-list, here: https://groups.google.com/a/chromium.org/forum/?utm_medium=email&utm_source=footer#!msg/chromium-dev/PA08hu52-v8/0RiYcbB7BQAJ). After turning off Windows Defender, compile perf improved to the expected ~10% slower. So folks finding this bug: Try turning off Windows Defender. |
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Comment 1 by tikuta@chromium.org
, Oct 16 2017Is there some effort to make clang{,-cl} faster? clang's speed up is very important for overall build time improvement.