Re: [PATCH] malloc: Revert fastbins to old-style atomics

[Florian Weimer <fweimer at redhat dot com>]

* Carlos O'Donell:

> On 1/16/19 10:33 AM, Florian Weimer wrote:
>> * 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>
>
> OK for master. Siddhesh needs to approve.

Siddhesh, is this okay to commit before the release?

Thanks,
Florian