Messages in this thread | | | Subject | Regression in 2.6.27-rc1 for set_cpus_allowed_ptr | Date | Fri, 8 Aug 2008 14:44:00 -0500 | From | "Langsdorf, Mark" <> |
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One of my co-workers noticed that the powernow-k8 driver no longer restarts when a CPU core is hot-disabled and then hot-enabled on AMD quad-core systems.
The following comands work fine on 2.6.26 and fail on 2.6.27-rc1:
echo 0 > /sys/devices/system/cpu/cpu3/online echo 1 > /sys/devices/system/cpu/cpu3/online find /sys -name cpufreq
For 2.6.26, the find will return a cpufreq directory for each processor. In 2.6.27-rc1, the cpu3 directory is missing.
After digging through the code, the following logic is failing when the core is hot-enabled at runtime. The code works during the boot sequence.
cpumask_t = current->cpus_allowed; set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu)); if (smp_processor_id() != cpu) return -ENODEV;
The objective is to move to the specific CPU and test it's MSRs to see if it is supported. For some reason, it isn't working. Any suggestions on how to fix this are appreciated.
-Mark Langdsorf Operating System Research Center AMD
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