[PATCH] D77144: [NFC] Remove waymarking because it improves performances

Tue Mar 31 14:53:14 PDT 2020

nikic added a comment.

I also ran the numbers, results are pretty similar to what you're seeing: instructions <http://llvm-compile-time-tracker.com/compare.php?from=c726c920e04046da29e403d55aa9c0e466b13959&to=4b7edeb688e3ee3ba99b6db1b876d16bd212ec6f&stat=instructions>, max-rss <http://llvm-compile-time-tracker.com/compare.php?from=c726c920e04046da29e403d55aa9c0e466b13959&to=4b7edeb688e3ee3ba99b6db1b876d16bd212ec6f&stat=max-rss>.

I suspect that we might not be seeing the whole picture here though. I couldn't find the original discussion on this, but https://github.com/ggreif/EuroLLVM-Waymarking mentions that at the time it was introduced, waymarking was a 2.5% compile-time regression, but saved 12% memory on some large C++ workloads. We're clearly not seeing anything close to a 12% memory regression here, but it's not clear whether that's because memory usage characteristics in LLVM changed significantly over the last 12 years (which doesn't seem unplausible), or whether waymarking needs heavier workloads to really shine.

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https://reviews.llvm.org/D77144