Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: Regression in 2.6.27-rc1 for set_cpus_allowed_ptr | Date | Fri, 8 Aug 2008 23:03:39 +0200 |
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[Adding CCs]
On Friday, 8 of August 2008, Langsdorf, Mark wrote: > 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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