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sched: Validate assumptions in sched_init_numa()
Add some code to validate assumptions we're making and output warnings if they are not. If this trigger we want to know about it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Alex Shi <lkml.alex@gmail.com> Link: http://lkml.kernel.org/n/tip-6uc3wk5s9udxtdl9cnku0vtt@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
Ingo Molnar
parent
c3decf0dfb
commit
d039ac6080
@ -5556,15 +5556,20 @@ static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
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#ifdef CONFIG_SCHED_DEBUG
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static __read_mostly int sched_domain_debug_enabled;
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static __read_mostly int sched_debug_enabled;
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static int __init sched_domain_debug_setup(char *str)
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static int __init sched_debug_setup(char *str)
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{
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sched_domain_debug_enabled = 1;
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sched_debug_enabled = 1;
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return 0;
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}
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early_param("sched_debug", sched_domain_debug_setup);
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early_param("sched_debug", sched_debug_setup);
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static inline bool sched_debug(void)
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{
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return sched_debug_enabled;
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}
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static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
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struct cpumask *groupmask)
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@ -5657,7 +5662,7 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu)
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{
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int level = 0;
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if (!sched_domain_debug_enabled)
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if (!sched_debug_enabled)
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return;
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if (!sd) {
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@ -5678,6 +5683,10 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu)
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}
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#else /* !CONFIG_SCHED_DEBUG */
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# define sched_domain_debug(sd, cpu) do { } while (0)
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static inline bool sched_debug(void)
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{
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return false;
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}
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#endif /* CONFIG_SCHED_DEBUG */
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static int sd_degenerate(struct sched_domain *sd)
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@ -6373,7 +6382,6 @@ static struct sched_domain_topology_level *sched_domain_topology = default_topol
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#ifdef CONFIG_NUMA
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static int sched_domains_numa_levels;
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static int sched_domains_numa_scale;
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static int *sched_domains_numa_distance;
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static struct cpumask ***sched_domains_numa_masks;
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static int sched_domains_curr_level;
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@ -6438,6 +6446,42 @@ static const struct cpumask *sd_numa_mask(int cpu)
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return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
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}
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static void sched_numa_warn(const char *str)
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{
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static int done = false;
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int i,j;
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if (done)
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return;
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done = true;
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printk(KERN_WARNING "ERROR: %s\n\n", str);
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for (i = 0; i < nr_node_ids; i++) {
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printk(KERN_WARNING " ");
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for (j = 0; j < nr_node_ids; j++)
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printk(KERN_CONT "%02d ", node_distance(i,j));
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printk(KERN_CONT "\n");
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}
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printk(KERN_WARNING "\n");
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}
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static bool find_numa_distance(int distance)
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{
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int i;
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if (distance == node_distance(0, 0))
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return true;
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for (i = 0; i < sched_domains_numa_levels; i++) {
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if (sched_domains_numa_distance[i] == distance)
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return true;
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}
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return false;
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}
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static void sched_init_numa(void)
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{
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int next_distance, curr_distance = node_distance(0, 0);
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@ -6445,7 +6489,6 @@ static void sched_init_numa(void)
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int level = 0;
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int i, j, k;
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sched_domains_numa_scale = curr_distance;
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sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
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if (!sched_domains_numa_distance)
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return;
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@ -6456,23 +6499,41 @@ static void sched_init_numa(void)
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*
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* Assumes node_distance(0,j) includes all distances in
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* node_distance(i,j) in order to avoid cubic time.
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*
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* XXX: could be optimized to O(n log n) by using sort()
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*/
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next_distance = curr_distance;
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for (i = 0; i < nr_node_ids; i++) {
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for (j = 0; j < nr_node_ids; j++) {
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int distance = node_distance(0, j);
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if (distance > curr_distance &&
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(distance < next_distance ||
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next_distance == curr_distance))
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next_distance = distance;
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for (k = 0; k < nr_node_ids; k++) {
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int distance = node_distance(i, k);
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if (distance > curr_distance &&
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(distance < next_distance ||
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next_distance == curr_distance))
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next_distance = distance;
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/*
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* While not a strong assumption it would be nice to know
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* about cases where if node A is connected to B, B is not
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* equally connected to A.
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*/
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if (sched_debug() && node_distance(k, i) != distance)
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sched_numa_warn("Node-distance not symmetric");
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if (sched_debug() && i && !find_numa_distance(distance))
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sched_numa_warn("Node-0 not representative");
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}
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if (next_distance != curr_distance) {
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sched_domains_numa_distance[level++] = next_distance;
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sched_domains_numa_levels = level;
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curr_distance = next_distance;
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} else break;
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}
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if (next_distance != curr_distance) {
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sched_domains_numa_distance[level++] = next_distance;
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sched_domains_numa_levels = level;
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curr_distance = next_distance;
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} else break;
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/*
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* In case of sched_debug() we verify the above assumption.
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*/
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if (!sched_debug())
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break;
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}
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/*
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* 'level' contains the number of unique distances, excluding the
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