Messages in this thread Patch in this message | | | Subject | [PATCH] sched: sched_best_cpu | From | Frank Cornelis <> | Date | 22 Aug 2003 14:32:39 +0200 |
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Hi,
I repatched it against the latest bk. This patch favors the local node more than the others to prevent unnecessary task migration by doing a better estimation of the after-migration load (see inline C documentation).
Frank.
sched.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-)
diff -Nru a/kernel/sched.c b/kernel/sched.c --- a/kernel/sched.c Thu Aug 21 16:10:41 2003 +++ b/kernel/sched.c Thu Aug 21 16:10:41 2003 @@ -793,29 +793,33 @@ */ static int sched_best_cpu(struct task_struct *p) { - int i, minload, load, best_cpu, node = 0; + int i, minload, load, best_cpu, node, pnode; cpumask_t cpumask; best_cpu = task_cpu(p); if (cpu_rq(best_cpu)->nr_running <= 2) return best_cpu; - minload = 10000000; + minload = INT_MAX; + node = pnode = cpu_to_node(best_cpu); for_each_node_with_cpus(i) { /* * Node load is always divided by nr_cpus_node to normalise * load values in case cpu count differs from node to node. - * We first multiply node_nr_running by 10 to get a little - * better resolution. + * If node != our node we add the load of the migrating task; + * we only want to migrate if: + * load(other node) + 1 < load(our node) - 1 + * The '+ 1' and '- 1' denote the migration. + * We multiply by NR_CPUS for best resolution. */ - load = 10 * atomic_read(&node_nr_running[i]) / nr_cpus_node(i); + load = NR_CPUS * (atomic_read(&node_nr_running[i]) + ((i != pnode) << 1)) / nr_cpus_node(i); if (load < minload) { minload = load; node = i; } } - minload = 10000000; + minload = INT_MAX; cpumask = node_to_cpumask(node); for (i = 0; i < NR_CPUS; ++i) { if (!cpu_isset(i, cpumask))
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