libcfs cpu partition can't support CPU hotplug, but it is safe when plug-in new CPU or enabling/disabling hyper-threading. It has potential risk only if plug-out CPU because it may break CPU affinity of Lustre threads.
Current libcfs will print warning for all CPU notification, this patch changed this behavior and only output warning when we lost all HTs in a CPU core which may have broken affinity of Lustre threads. Signed-off-by: Liang Zhen <liang.z...@intel.com> Reviewed-on: http://review.whamcloud.com/8770 Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4454 Reviewed-by: Bobi Jam <bobi...@gmail.com> Reviewed-by: Andreas Dilger <andreas.dil...@intel.com> Signed-off-by: Oleg Drokin <oleg.dro...@intel.com> --- .../staging/lustre/lustre/libcfs/linux/linux-cpu.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/staging/lustre/lustre/libcfs/linux/linux-cpu.c b/drivers/staging/lustre/lustre/libcfs/linux/linux-cpu.c index 58bb256..77b1ef6 100644 --- a/drivers/staging/lustre/lustre/libcfs/linux/linux-cpu.c +++ b/drivers/staging/lustre/lustre/libcfs/linux/linux-cpu.c @@ -952,6 +952,7 @@ static int cfs_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { unsigned int cpu = (unsigned long)hcpu; + bool warn; switch (action) { case CPU_DEAD: @@ -962,9 +963,21 @@ cfs_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) cpt_data.cpt_version++; spin_unlock(&cpt_data.cpt_lock); default: - CWARN("Lustre: can't support CPU hotplug well now, " - "performance and stability could be impacted" - "[CPU %u notify: %lx]\n", cpu, action); + if (action != CPU_DEAD && action != CPU_DEAD_FROZEN) { + CDEBUG(D_INFO, "CPU changed [cpu %u action %lx]\n", + cpu, action); + break; + } + + down(&cpt_data.cpt_mutex); + /* if all HTs in a core are offline, it may break affinity */ + cfs_cpu_ht_siblings(cpu, cpt_data.cpt_cpumask); + warn = any_online_cpu(*cpt_data.cpt_cpumask) >= nr_cpu_ids; + up(&cpt_data.cpt_mutex); + CDEBUG(warn ? D_WARNING : D_INFO, + "Lustre: can't support CPU plug-out well now, " + "performance and stability could be impacted " + "[CPU %u action: %lx]\n", cpu, action); } return NOTIFY_OK; -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
