2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ Commit: aa483808516ca5cacfa0e5849691f64fec25828e upstream The idea was suggested by Peter Zijlstra here: http://marc.info/?l=linux-kernel&m=127476934517534&w=2 irq time is technically not available to the tasks running on the CPU. This patch removes irq time from CPU power piggybacking on sched_rt_avg_update(). Tested this by keeping CPU X busy with a network intensive task having 75% oa a single CPU irq processing (hard+soft) on a 4-way system. And start seven cycle soakers on the system. Without this change, there will be two tasks on each CPU. With this change, there is a single task on irq busy CPU X and remaining 7 tasks are spread around among other 3 CPUs. Signed-off-by: Venkatesh Pallipadi <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Signed-off-by: Andi Kleen <[email protected]> LKML-Reference: <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Mike Galbraith <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/sched.c | 18 ++++++++++++++++++ kernel/sched_fair.c | 7 ++++++- kernel/sched_features.h | 5 +++++ 3 files changed, 29 insertions(+), 1 deletion(-) Index: linux-2.6.35.y/kernel/sched.c =================================================================== --- linux-2.6.35.y.orig/kernel/sched.c 2011-03-29 23:03:00.319292001 -0700 +++ linux-2.6.35.y/kernel/sched.c 2011-03-29 23:54:58.951494004 -0700 @@ -519,6 +519,10 @@ u64 avg_idle; #endif +#ifdef CONFIG_IRQ_TIME_ACCOUNTING + u64 prev_irq_time; +#endif + /* calc_load related fields */ unsigned long calc_load_update; long calc_load_active; @@ -643,6 +647,7 @@ #endif /* CONFIG_CGROUP_SCHED */ static u64 irq_time_cpu(int cpu); +static void sched_irq_time_avg_update(struct rq *rq, u64 irq_time); inline void update_rq_clock(struct rq *rq) { @@ -654,6 +659,8 @@ irq_time = irq_time_cpu(cpu); if (rq->clock - irq_time > rq->clock_task) rq->clock_task = rq->clock - irq_time; + + sched_irq_time_avg_update(rq, irq_time); } /* @@ -1895,6 +1902,15 @@ local_irq_restore(flags); } +static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) +{ + if (sched_clock_irqtime && sched_feat(NONIRQ_POWER)) { + u64 delta_irq = curr_irq_time - rq->prev_irq_time; + rq->prev_irq_time = curr_irq_time; + sched_rt_avg_update(rq, delta_irq); + } +} + #else static u64 irq_time_cpu(int cpu) @@ -1902,6 +1918,8 @@ return 0; } +static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) { } + #endif #include "sched_stats.h" Index: linux-2.6.35.y/kernel/sched_features.h =================================================================== --- linux-2.6.35.y.orig/kernel/sched_features.h 2011-03-29 22:51:28.061005159 -0700 +++ linux-2.6.35.y/kernel/sched_features.h 2011-03-29 23:03:00.345291335 -0700 @@ -61,3 +61,8 @@ * release the lock. Decreases scheduling overhead. */ SCHED_FEAT(OWNER_SPIN, 1) + +/* + * Decrement CPU power based on irq activity + */ +SCHED_FEAT(NONIRQ_POWER, 1) Index: linux-2.6.35.y/kernel/sched_fair.c =================================================================== --- linux-2.6.35.y.orig/kernel/sched_fair.c 2011-03-29 23:03:00.320291975 -0700 +++ linux-2.6.35.y/kernel/sched_fair.c 2011-03-29 23:54:58.089516061 -0700 @@ -2276,8 +2276,13 @@ u64 total, available; total = sched_avg_period() + (rq->clock - rq->age_stamp); - available = total - rq->rt_avg; + if (unlikely(total < rq->rt_avg)) { + /* Ensures that power won't end up being negative */ + available = 0; + } else { + available = total - rq->rt_avg; + } if (unlikely((s64)total < SCHED_LOAD_SCALE)) total = SCHED_LOAD_SCALE; _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
