From 6fd67d8581106f59fdfe07b283477ffd7864dbb9 Mon Sep 17 00:00:00 2001 From: Oleg Drokin Date: Fri, 28 Feb 2014 21:16:46 -0500 Subject: [PATCH] lustre/libcfs: warn if all HTs in a core are gone 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 Reviewed-on: http://review.whamcloud.com/8770 Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4454 Reviewed-by: Bobi Jam Reviewed-by: Andreas Dilger Signed-off-by: Oleg Drokin Signed-off-by: Greg Kroah-Hartman --- .../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 58bb256ee04..77b1ef64ecc 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; -- 2.46.0