Messages in this thread |  | | Date | Sat, 10 Aug 2013 16:00:51 -0700 | | From | "H. Peter Anvin" <> | | Subject | Re: Re-tune x86 uaccess code for PREEMPT_VOLUNTARY |
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On 08/10/2013 11:51 AM, Linus Torvalds wrote: > Note that you still want the *test* to be done in C code, because together > with "unlikely()" you'd likely do pretty close to optimal code > generation, and hiding the decrement and test and conditional jump in > asm you wouldn't get the proper instruction scheduling and branch > following that gcc does.
How much instruction scheduling can gcc actually do given that there is a barrier involved? I guess some on the RISC architectures which need load/subtract/store...
-hpa
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