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authorSuresh Siddha <suresh.b.siddha@intel.com>2007-07-19 21:28:35 +0200
committerIngo Molnar <mingo@elte.hu>2007-07-19 21:28:35 +0200
commit9439aab8dbc33c2c03c3a19dba267360383ba38c (patch)
treeb6405b709b7bf60216290f9d81aec133faea6adf
parentc41917df8a1adde34864116ce2231a7fe308d2ff (diff)
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[PATCH] sched: fix newly idle load balance in case of SMT
In the presence of SMT, newly idle balance was never happening for multi-core and SMP domains (even when both the logical siblings are idle). If thread 0 is already idle and when thread 1 is about to go to idle, newly idle load balance always think that one of the threads is not idle and skips doing the newly idle load balance for multi-core and SMP domains. This is because of the idle_cpu() macro, which checks if the current process on a cpu is an idle process. But this is not the case for the thread doing the load_balance_newidle(). Fix this by using runqueue's nr_running field instead of idle_cpu(). And also skip the logic of 'only one idle cpu in the group will be doing load balancing' during newly idle case. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 645256b228c..e36d99d1ddb 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2235,7 +2235,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
rq = cpu_rq(i);
- if (*sd_idle && !idle_cpu(i))
+ if (*sd_idle && rq->nr_running)
*sd_idle = 0;
/* Bias balancing toward cpus of our domain */
@@ -2257,9 +2257,11 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
/*
* First idle cpu or the first cpu(busiest) in this sched group
* is eligible for doing load balancing at this and above
- * domains.
+ * domains. In the newly idle case, we will allow all the cpu's
+ * to do the newly idle load balance.
*/
- if (local_group && balance_cpu != this_cpu && balance) {
+ if (idle != CPU_NEWLY_IDLE && local_group &&
+ balance_cpu != this_cpu && balance) {
*balance = 0;
goto ret;
}