Messages in this thread | | | From | Andres Freund <> | Subject | | Date | Fri, 9 May 2014 03:29:15 +0200 |
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Hi,
After 3.14 I noticed that perf started to only support software events.
The reason - found after a some staring deathmatches because the patches look innocent - is a typo in __flip_bit() introduced by 22085a66c2fab6cf9b9393c056a3600a6b4735de which only takes effect after c0a639ad0bc6b178b46996bd1f821a04643e2bde. Due to the typo no msr writes via either msr_clear/set_bit actually write back the new value. That then causes cpuid limits not to be lifted causing 'my' perf and very likely some other problems.
There's also a typo in the former commit which makes it impossible to actually use the MSR_IA32_MISC_ENABLE_LIMIT_CPUID macro correctly.
Regards,
Andres Freund
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