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Re: [PATCH] malloc: Revert fastbins to old-style atomics
* Carlos O'Donell:
> On 1/16/19 8:04 AM, Florian Weimer wrote:
>> Commit 6923f6db1e688dedcf3a6556da76e0bf24a41872 ("malloc: Use current
>> (C11-style) atomics for fastbin access") caused a substantial
>> performance regression on POWER and Aarch64, and the old atomics,
>> while hard to prove correct, seem to work in practice.
>
> Why is it slow?
>
> What do the benchmarks say?
>
> What does profiling show to be the slow instruction?
>
> How is the instruction sequence different from before that causes the
> problem?
The other thread is here:
<https://sourceware.org/ml/libc-alpha/2019-01/msg00379.html>
Thanks,
Florian