Messages in this thread | | | Date | Thu, 22 Oct 2015 18:41:30 -0700 | From | Leonid Yegoshin <> | Subject | Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() |
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You can not use R4K CP0_count in SMP (multicore) without core-specific adjustment. After first power-saving with core clock off or core down the values in CP0_count in different cores are absolutely different.
Until you include in system a patch like http://patchwork.linux-mips.org/patch/10871/
"MIPS: Setup an instruction emulation in VDSO protected page instead of user stack"
which creates a per-thread memory and put into that memory an adjustment value (which can be changed during re-schedule to another core), the use of R4K counter is incorrect in SMP environment.
Note: It is also possible to setup and maintain a per-core page with that value too as an alternative variant for adjustment.
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