[Xen-devel] [PATCH 57/60] xen/sched: support multiple cpus per scheduling resource

[Juergen Gross <jgross@xxxxxxxx>]

Prepare supporting multiple cpus per scheduling resource by allocating
the cpumask per resource dynamically.

Modify sched_res_mask to have only one bit per scheduling resource set.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V1: new patch (carved out from other patch)
---
 xen/common/schedule.c      | 16 ++++++++++++++--
 xen/include/xen/sched-if.h |  4 ++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 78eb055d07..6f6886d5c3 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -59,7 +59,7 @@ integer_param("sched_ratelimit_us", sched_ratelimit_us);
 enum sched_gran opt_sched_granularity = SCHED_GRAN_cpu;
 unsigned int sched_granularity = 1;
 bool sched_disable_smt_switching;
-const cpumask_t *sched_res_mask = &cpumask_all;
+cpumask_var_t sched_res_mask;
 
 /* Common lock for free cpus. */
 static DEFINE_SPINLOCK(sched_free_cpu_lock);
@@ -2288,8 +2288,14 @@ static int cpu_schedule_up(unsigned int cpu)
     sd = xzalloc(struct sched_resource);
     if ( sd == NULL )
         return -ENOMEM;
+    if ( !zalloc_cpumask_var(&sd->cpus) )
+    {
+        xfree(sd);
+        return -ENOMEM;
+    }
+
     sd->processor = cpu;
-    sd->cpus = cpumask_of(cpu);
+    cpumask_copy(sd->cpus, cpumask_of(cpu));
     set_sched_res(cpu, sd);
 
     sd->scheduler = &sched_idle_ops;
@@ -2301,6 +2307,8 @@ static int cpu_schedule_up(unsigned int cpu)
     /* We start with cpu granularity. */
     sd->granularity = 1;
 
+    cpumask_set_cpu(cpu, sched_res_mask);
+
     /* Boot CPU is dealt with later in schedule_init(). */
     if ( cpu == 0 )
         return 0;
@@ -2336,6 +2344,7 @@ static void sched_res_free(struct rcu_head *head)
 {
     struct sched_resource *sd = container_of(head, struct sched_resource, rcu);
 
+    free_cpumask_var(sd->cpus);
     xfree(sd);
 }
 
@@ -2484,6 +2493,9 @@ void __init scheduler_init(void)
         printk("Using '%s' (%s)\n", ops.name, ops.opt_name);
     }
 
+    if ( !zalloc_cpumask_var(&sched_res_mask) )
+        BUG();
+
     if ( cpu_schedule_up(0) )
         BUG();
     register_cpu_notifier(&cpu_schedule_nfb);
diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index abf6d0522d..714d793815 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -24,7 +24,7 @@ extern cpumask_t cpupool_free_cpus;
 extern int sched_ratelimit_us;
 
 /* Scheduling resource mask. */
-extern const cpumask_t *sched_res_mask;
+extern cpumask_var_t sched_res_mask;
 
 /* Number of vcpus per struct sched_unit. */
 enum sched_gran {
@@ -58,7 +58,7 @@ struct sched_resource {
     atomic_t            urgent_count;   /* how many urgent vcpus           */
     unsigned int        processor;
     unsigned int        granularity;
-    const cpumask_t    *cpus;           /* cpus covered by this struct     */
+    cpumask_var_t       cpus;           /* cpus covered by this struct     */
     struct rcu_head     rcu;
 };
 
-- 
2.16.4


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