lustre/libcfs: warn if all HTs in a core are gone (6fd67d85) · Commits · 戴 / test

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.zhen@intel.com> Reviewed-on: http://review.whamcloud.com/8770 Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4454 Reviewed-by:

Bobi Jam <bobijam@gmail.com> Reviewed-by:

Andreas Dilger <andreas.dilger@intel.com> Signed-off-by:

Oleg Drokin <oleg.drokin@intel.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/libcfs/linux/linux-cpu.c

+16 −3

Original line number	Diff line number	Diff line
		@@ -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, "
		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 notify: %lx]\n", cpu, action);
		"[CPU %u action: %lx]\n", cpu, action);
		}

		return NOTIFY_OK;

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