From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp02.au.ibm.com (e23smtp02.au.ibm.com [202.81.31.144]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp02.au.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 795512C00B6 for ; Tue, 23 Jul 2013 22:33:55 +1000 (EST) Received: from /spool/local by e23smtp02.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 23 Jul 2013 22:23:27 +1000 Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [9.190.235.152]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 7A22A2CE8051 for ; Tue, 23 Jul 2013 22:33:48 +1000 (EST) Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r6NCIFUa10879340 for ; Tue, 23 Jul 2013 22:18:16 +1000 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r6NCXkQ0024929 for ; Tue, 23 Jul 2013 22:33:47 +1000 Date: Tue, 23 Jul 2013 07:33:44 -0500 From: Robert Jennings To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH] powerpc: VPHN topology change updates all siblings Message-ID: <20130723123344.GA11611@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: stable@vger.kernel.org, Paul Mackerras , Nathan Fontenot , Robert Jennings , Jan Stancek List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , When an associativity level change is found for one thread, the siblings threads need to be updated as well. This is done today for PRRN in stage_topology_update() but is missing for VPHN in update_cpu_associativity_changes_mask(). All threads should be updated to move to the new node. Without this patch, a single thread may be flagged for a topology change, leaving it in a different node from its siblings, which is incorrect. This causes problems for the scheduler where overlapping scheduler groups are created and a loop is formed in those groups. Reported-by: Jan Stancek Signed-off-by: Robert Jennings Cc: --- Looking to get this fix in 3.11. This is requested for the 3.10 stable tree as well, it fixes a bug that presents as a scheduler issue when VPHN is active. VPHN was enabled in the v3.9 window in commit b7abef0. --- arch/powerpc/mm/numa.c | 59 +++++++++++++++++++++++++++++++++++++------------- 1 file changed, 44 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c index 0839721..5850798 100644 --- a/arch/powerpc/mm/numa.c +++ b/arch/powerpc/mm/numa.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -1318,7 +1319,8 @@ static int update_cpu_associativity_changes_mask(void) } } if (changed) { - cpumask_set_cpu(cpu, changes); + cpumask_or(changes, changes, cpu_sibling_mask(cpu)); + cpu = cpu_last_thread_sibling(cpu); } } @@ -1426,7 +1428,7 @@ static int update_cpu_topology(void *data) if (!data) return -EINVAL; - cpu = get_cpu(); + cpu = smp_processor_id(); for (update = data; update; update = update->next) { if (cpu != update->cpu) @@ -1446,12 +1448,12 @@ static int update_cpu_topology(void *data) */ int arch_update_cpu_topology(void) { - unsigned int cpu, changed = 0; + unsigned int cpu, sibling, changed = 0; struct topology_update_data *updates, *ud; unsigned int associativity[VPHN_ASSOC_BUFSIZE] = {0}; cpumask_t updated_cpus; struct device *dev; - int weight, i = 0; + int weight, new_nid, i = 0; weight = cpumask_weight(&cpu_associativity_changes_mask); if (!weight) @@ -1464,19 +1466,46 @@ int arch_update_cpu_topology(void) cpumask_clear(&updated_cpus); for_each_cpu(cpu, &cpu_associativity_changes_mask) { - ud = &updates[i++]; - ud->cpu = cpu; - vphn_get_associativity(cpu, associativity); - ud->new_nid = associativity_to_nid(associativity); - - if (ud->new_nid < 0 || !node_online(ud->new_nid)) - ud->new_nid = first_online_node; + /* + * If siblings aren't flagged for changes, updates list + * will be too short. Skip on this update and set for next + * update. + */ + if (!cpumask_subset(cpu_sibling_mask(cpu), + &cpu_associativity_changes_mask)) { + pr_info("Sibling bits not set for associativity " + "change, cpu%d\n", cpu); + cpumask_or(&cpu_associativity_changes_mask, + &cpu_associativity_changes_mask, + cpu_sibling_mask(cpu)); + cpu = cpu_last_thread_sibling(cpu); + continue; + } - ud->old_nid = numa_cpu_lookup_table[cpu]; - cpumask_set_cpu(cpu, &updated_cpus); + /* Use associativity from first thread for all siblings */ + vphn_get_associativity(cpu, associativity); + new_nid = associativity_to_nid(associativity); + if (new_nid < 0 || !node_online(new_nid)) + new_nid = first_online_node; + + if (new_nid == numa_cpu_lookup_table[cpu]) { + cpumask_andnot(&cpu_associativity_changes_mask, + &cpu_associativity_changes_mask, + cpu_sibling_mask(cpu)); + cpu = cpu_last_thread_sibling(cpu); + continue; + } - if (i < weight) - ud->next = &updates[i]; + for_each_cpu(sibling, cpu_sibling_mask(cpu)) { + ud = &updates[i++]; + ud->cpu = sibling; + ud->new_nid = new_nid; + ud->old_nid = numa_cpu_lookup_table[sibling]; + cpumask_set_cpu(sibling, &updated_cpus); + if (i < weight) + ud->next = &updates[i]; + } + cpu = cpu_last_thread_sibling(cpu); } stop_machine(update_cpu_topology, &updates[0], &updated_cpus); -- 1.8.1.2