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

Wed Apr 1 00:32:14 PDT 2020

ekatz added a subscriber: ggreif.
ekatz added a comment.

Let me shed a little light on the Waymarking algorithm:

It all began with @ggreif, in 2008.
He proposed the the //Waymarking// as a solution in LLVM Data Structures, and Putting Use on Diet <http://heisenbug.blogspot.com/2008/04/llvm-data-structures-and-putting-use-on.html>.

As a solution, he opened a branch called `use-diet` in the LLVM SVN repository, which was merged in rL50943 <https://reviews.llvm.org/rL50943> : rGf6caff66a1bf <https://reviews.llvm.org/rGf6caff66a1bfa6464e6a17c0bcfcf06a09a9b909>.

According to the his blog, in http://heisenbug.blogspot.com/2008/05/merged.html; I quote:
//"... the SPEC benchmark 447.dealII had a **13%** reduced memory footprint ..."//
and
//"... observed slight speedup on kimwitu++ benchmark's compilation time."//

In addition, according to @lattner's response in https://lists.llvm.org/pipermail/llvm-dev/2008-April/014151.html, the //Waymarking// seems to go up to even **15% improvement** in memory usage.

Regarding the removal of the //Waymarking//, don't get me wrong, I am all in for its simplicity, and performance improvements, but I'm afraid more investigation needs to be done.
Please try to test using the benchmarks mentioned above, and maybe even larger workloads (like the linux kernel, if you can; and I know, at least it part, if not in full, the AOSP is using clang).

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