Messages in this thread | | | Date | Tue, 13 Oct 2020 14:44:52 +0800 | From | Chen Yu <> | Subject | Re: [RFC][PATCH] cpufreq: intel_pstate: Delete intel_pstate sysfs if failed to register the driver |
| |
Hi Srinivas, On Mon, Oct 12, 2020 at 06:22:40AM -0700, srinivas pandruvada wrote: > On Fri, 2020-10-09 at 11:30 +0800, Chen Yu wrote: > > There is a corner case that if the intel_pstate driver failed to be > > registered(might be due to invalid MSR access) > Do you have logs why it is not loaded? On supported platforms MSRs > should be invalid. Unfortunately we don't have the boot up log for now, as it is a pre-production platform and the low-level simulation(for MSR) might be unstable.( And there seems to be some environment issue on pre-production platform to reproduce this issue). But we can hack the code in intel_pstate to make the driver failed to be loaded and the issue was reproduced. > It may be a case when we are trying to bring up pre-production systems > where some instability in MSRs on certain CPUs. > > But the patch is correct. We can't have invalid folder when > intel_pstate is not used. > > > and with the acpi_cpufreq > > loaded, the intel_pstate sysfs might still be created, which makes > > the > > user confusing(turbostat for example): > > > > grep . /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver > > acpi-cpufreq > > > > grep . /sys/devices/system/cpu/intel_pstate/* > > /sys/devices/system/cpu/intel_pstate/max_perf_pct:0 > > /sys/devices/system/cpu/intel_pstate/min_perf_pct:0 > > grep: /sys/devices/system/cpu/intel_pstate/no_turbo: Resource > > temporarily unavailable > > grep: /sys/devices/system/cpu/intel_pstate/num_pstates: Resource > > temporarily unavailable > > /sys/devices/system/cpu/intel_pstate/status:off > > grep: /sys/devices/system/cpu/intel_pstate/turbo_pct: Resource > > temporarily unavailable > > > > The existing of intel_pstate sysfs does not mean that the > > intel_pstate driver > > has been successfully loaded(for example, echo off to status), but > > the > > intel_pstate sysfs should not co-exist when acpi-cpufreq is also > > present. > > Fix this issue by deleting the intel_pstate sysfs if the driver > > failed > > to be loaded during bootup. > > > > Reported-by: Wendy Wang <wendy.wang@intel.com> > > Suggested-by: Zhang Rui <rui.zhang@intel.com> > > Signed-off-by: Chen Yu <yu.c.chen@intel.com> > Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com Thanks!
Best, Chenyu
| |