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drivers/perf: xgene: Add CPU hotplug support

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If the CPU assigned to the xgene PMU is taken offline, then subsequent
perf invocations on the PMU will fail:

  # echo 0 > /sys/devices/system/cpu/cpu0/online
  # perf stat -a -e l3c0/cycle-count/,l3c0/write/ sleep 1
    Error:
    The sys_perf_event_open() syscall returned with 19 (No such device) for event (l3c0/cycle-count/).
    /bin/dmesg may provide additional information.
    No CONFIG_PERF_EVENTS=y kernel support configured?

This patch implements a hotplug notifier in the xgene PMU driver so that
the PMU context is migrated to another online CPU should its assigned
CPU disappear.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Hoan Tran <hoan.tran@amperecomputing.com>
[will: Made naming of new cpuhp_state enum entry consistent]
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Hoan Tran
2018-11-07 19:40:58 +00:00
committed by Will Deacon
parent 472dc9fa7c
commit cbb72a3c19
2 changed files with 74 additions and 7 deletions
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1
include/linux/cpuhotplug.h
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@@ -164,6 +164,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_ARM_L2X0_ONLINE,
CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
CPUHP_AP_PERF_ARM_APM_XGENE_ONLINE,
CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,