[Xen-changelog] [xen master] xen: credit2: allocate runqueue data structure dynamically

[patchbot@xxxxxxx]

commit efda30d5916f8eac538faf59d4338d150e034f1b
Author:     Dario Faggioli <dario.faggioli@xxxxxxxxxx>
AuthorDate: Fri Jun 23 12:54:52 2017 +0200
Commit:     George Dunlap <george.dunlap@xxxxxxxxxx>
CommitDate: Fri Jul 21 18:21:23 2017 +0100

    xen: credit2: allocate runqueue data structure dynamically
    
    Instead of keeping an NR_CPUS big array of csched2_runqueue_data
    elements, directly inside the csched2_private structure, allocate
    it dynamically.
    
    This has two positive effects:
    - reduces the size of csched2_private sensibly, which is
      especially good in case there are more instance of Credit2
      (in different cpupools), and is also good from the point
      of view of fitting the struct into CPU caches;
    - we can use nr_cpu_ids as array size, which may be sensibly
      smaller than NR_CPUS
    
    Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
    Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
---
 xen/common/sched_credit2.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index b9b9283..4ae4e4b 100644
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -390,7 +390,7 @@ struct csched2_private {
 
     int runq_map[NR_CPUS];
     cpumask_t active_queues; /* Queues which may have active cpus */
-    struct csched2_runqueue_data rqd[NR_CPUS];
+    struct csched2_runqueue_data *rqd;
 
     unsigned int load_precision_shift;
     unsigned int load_window_shift;
@@ -3106,9 +3106,11 @@ csched2_init(struct scheduler *ops)
     printk(XENLOG_INFO "load tracking window length %llu ns\n",
            1ULL << opt_load_window_shift);
 
-    /* Basically no CPU information is available at this point; just
+    /*
+     * Basically no CPU information is available at this point; just
      * set up basic structures, and a callback when the CPU info is
-     * available. */
+     * available.
+     */
 
     prv = xzalloc(struct csched2_private);
     if ( prv == NULL )
@@ -3118,7 +3120,13 @@ csched2_init(struct scheduler *ops)
     rwlock_init(&prv->lock);
     INIT_LIST_HEAD(&prv->sdom);
 
-    /* But un-initialize all runqueues */
+    /* Allocate all runqueues and mark them as un-initialized */
+    prv->rqd = xzalloc_array(struct csched2_runqueue_data, nr_cpu_ids);
+    if ( !prv->rqd )
+    {
+        xfree(prv);
+        return -ENOMEM;
+    }
     for ( i = 0; i < nr_cpu_ids; i++ )
     {
         prv->runq_map[i] = -1;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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