Messages in this thread | | | Date | Tue, 10 Sep 2013 09:24:21 -0700 | Subject | Re: [PATCH 0/7] preempt_count rework -v2 | From | Linus Torvalds <> |
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On Tue, Sep 10, 2013 at 8:29 AM, Arjan van de Ven <arjan@linux.intel.com> 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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