Re: [PATCH 0/7] preempt_count rework -v2

[Linus Torvalds]

On Tue, Sep 10, 2013 at 8:29 AM, Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> wrote:
>>
> also.. yuck on using "dec"
> "dec" sucks, please use "sub foo  ,1" instead

That's a bigger instruction, largely due to the constant.

> (dec sucks because of its broken flags behavior; it creates basically a
> bubble in the pipeline)

Intel could (and should) just fix that. It's "easy" enough - you just
need to rename the carry flag as a separate register (and make sure
that the conditional instructions that don't use it don't think they
need it).

In fact I thought Intel already did that on their large cores. Are you
sure they still have trouble with inc/dec?

           Linus
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