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Propeller slows down clang ~20% #181
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Unfortunately, I reproduced that result on AMD Ryzen 7700.
Processor:
Used OS:
Kernel:
Perf version:
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llvm18 use Fixed MBB ID(llvm/llvm-project@3d6841b). While autofdo now revert the code which support 'Fixed MBB ID' (ad3e924). I think it may be the reason. |
Has this issue been resolved?
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I use this code snap(llvm/llvm-project@3d6841b) and propeller seems work well with llvm16(I think llvm17 is ok). The reason is:
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I have tried to reproduce optimization clang with Propeller.
After all modifications described in #179 and #180, modified https://github.com/google/autofdo/blob/master/propeller_optimize_clang.sh started to work on my machine.
Unfortunately, the results looks very strange. Applying propeller to clang slows it down about 20%:
I used numactl to pin threads to HW cores. When I disables pins, the results were improved slightly, but, the gap between baseline and propeller continues to be significant:
In the case of pinned threads, propeller slightly decreased iTLB misses, while L1-icache-misses increased about 1.5x times.
Tested in RAM-disk on $ lscpu
Used OS:
Used linux kernel:
Gists:
with numactl:
https://gist.github.com/foxtran/b7fedfbb0bd036629448ce62d18bd7a6
without numactl:
https://gist.github.com/foxtran/fdc4abf8e2de127800f670b9edeeb9f2
Applied patches (with #179, #180):
for numactl:
Without numactl:
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