From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nishanth Aravamudan Date: Thu, 17 Jul 2014 23:09:58 +0000 Subject: [RFC 1/2] workqueue: use the nearest NUMA node, not the local one Message-Id: <20140717230958.GB32660@linux.vnet.ibm.com> List-Id: References: <20140717230923.GA32660@linux.vnet.ibm.com> In-Reply-To: <20140717230923.GA32660@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: benh@kernel.crashing.org Cc: Joonsoo Kim , David Rientjes , Wanpeng Li , Jiang Liu , Tony Luck , Fenghua Yu , linux-ia64@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org In the presence of memoryless nodes, the workqueue code incorrectly uses cpu_to_node() to determine what node to prefer memory allocations come from. cpu_to_mem() should be used instead, which will use the nearest NUMA node with memory. Signed-off-by: Nishanth Aravamudan diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 35974ac..0bba022 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3547,7 +3547,12 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) for_each_node(node) { if (cpumask_subset(pool->attrs->cpumask, wq_numa_possible_cpumask[node])) { - pool->node = node; + /* + * We could use local_memory_node(node) here, + * but it is expensive and the following caches + * the same value. + */ + pool->node = cpu_to_mem(cpumask_first(pool->attrs->cpumask)); break; } } @@ -4921,7 +4926,7 @@ static int __init init_workqueues(void) pool->cpu = cpu; cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); pool->attrs->nice = std_nice[i++]; - pool->node = cpu_to_node(cpu); + pool->node = cpu_to_mem(cpu); /* alloc pool ID */ mutex_lock(&wq_pool_mutex);