Messages in this thread | | | Date | Wed, 10 Mar 2021 09:13:24 -0500 | From | Steven Rostedt <> | Subject | Re: The killing of ideal_nops[] |
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On Wed, 10 Mar 2021 11:22:48 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> After this FEATURE_NOPL is unused except for required-features for > x86_64. FEATURE_K8 is only used for PTI and FEATURE_K7 is unused. > > AFAICT this negatively affects lots of 32bit (DONTCARE) and 32bit on > 64bit CPUs (CARELESS) and early AMD (K8) which is from 2003 and almost > 2 decades old by now (SHRUG). > > Everything x86_64 since AMD K10 (2007) was using p6_nops. > > And per FEATURE_NOPL being required for x86_64, all those CPUs can use > p6_nops. So stop caring about NOPs, simplify things and get on with life > :-)
Before ripping out all the ideal_nop logic, I wonder if we should just force the nops you want now (that is, don't change the selected ideal_nops, just "pretend" that the CPU wants p6_nops), and see if anyone complains. After a few releases, if there's no complaints, then we can rip out the ideal_nop logic.
-- Steve
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