Since cfs->{load_stamp,load_last} are zero-initalized the initial load update will consider the delta to be 'since the beginning of time'. This results in a lot of pointless divisions to bring this large period to be within the sysctl_sched_shares_window. Fix this by initializing load_stamp to be 1 at cfs_rq initialization, this allows for an initial load_stamp > load_last which then lets standard idle truncation proceed. We avoid spinning (and slightly improve consistency) by fixing delta to be [period - 1] in this path resulting in a slightly more predictable shares ramp. (Previously the amount of idle time preserved by the overflow would range between [period/2,period-1].) Signed-off-by: Paul Turner --- kernel/sched.c | 2 ++ kernel/sched_fair.c | 1 + 2 files changed, 3 insertions(+) Index: tip3/kernel/sched.c =================================================================== --- tip3.orig/kernel/sched.c +++ tip3/kernel/sched.c @@ -7796,6 +7796,8 @@ static void init_cfs_rq(struct cfs_rq *c INIT_LIST_HEAD(&cfs_rq->tasks); #ifdef CONFIG_FAIR_GROUP_SCHED cfs_rq->rq = rq; + /* allow initial update_cfs_load() to truncate */ + cfs_rq->load_stamp = 1; #endif cfs_rq->min_vruntime = (u64)(-(1LL << 20)); } Index: tip3/kernel/sched_fair.c =================================================================== --- tip3.orig/kernel/sched_fair.c +++ tip3/kernel/sched_fair.c @@ -732,6 +732,7 @@ static void update_cfs_load(struct cfs_r now - cfs_rq->load_last > 4 * period) { cfs_rq->load_period = 0; cfs_rq->load_avg = 0; + delta = period - 1; } cfs_rq->load_stamp = now; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/