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-rw-r--r--include/linux/cpumask.h8
-rw-r--r--lib/cpumask.c63
2 files changed, 71 insertions, 0 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index d08e4d2a9b92..d5ef249735d2 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -142,6 +142,13 @@ static inline unsigned int cpumask_any_but(const struct cpumask *mask,
return 1;
}
+static inline int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
+{
+ set_bit(0, cpumask_bits(dstp));
+
+ return 0;
+}
+
#define for_each_cpu(cpu, mask) \
for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
#define for_each_cpu_not(cpu, mask) \
@@ -192,6 +199,7 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
+int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp);
/**
* for_each_cpu - iterate over every cpu in a mask
diff --git a/lib/cpumask.c b/lib/cpumask.c
index b810b753c607..c101230658eb 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -164,3 +164,66 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask)
memblock_free_early(__pa(mask), cpumask_size());
}
#endif
+
+/**
+ * cpumask_set_cpu_local_first - set i'th cpu with local numa cpu's first
+ *
+ * @i: index number
+ * @numa_node: local numa_node
+ * @dstp: cpumask with the relevant cpu bit set according to the policy
+ *
+ * This function sets the cpumask according to a numa aware policy.
+ * cpumask could be used as an affinity hint for the IRQ related to a
+ * queue. When the policy is to spread queues across cores - local cores
+ * first.
+ *
+ * Returns 0 on success, -ENOMEM for no memory, and -EAGAIN when failed to set
+ * the cpu bit and need to re-call the function.
+ */
+int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
+{
+ cpumask_var_t mask;
+ int cpu;
+ int ret = 0;
+
+ if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
+ return -ENOMEM;
+
+ i %= num_online_cpus();
+
+ if (!cpumask_of_node(numa_node)) {
+ /* Use all online cpu's for non numa aware system */
+ cpumask_copy(mask, cpu_online_mask);
+ } else {
+ int n;
+
+ cpumask_and(mask,
+ cpumask_of_node(numa_node), cpu_online_mask);
+
+ n = cpumask_weight(mask);
+ if (i >= n) {
+ i -= n;
+
+ /* If index > number of local cpu's, mask out local
+ * cpu's
+ */
+ cpumask_andnot(mask, cpu_online_mask, mask);
+ }
+ }
+
+ for_each_cpu(cpu, mask) {
+ if (--i < 0)
+ goto out;
+ }
+
+ ret = -EAGAIN;
+
+out:
+ free_cpumask_var(mask);
+
+ if (!ret)
+ cpumask_set_cpu(cpu, dstp);
+
+ return ret;
+}
+EXPORT_SYMBOL(cpumask_set_cpu_local_first);

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