From c52f14d384628db0217a7a9080ab800d5ffb2d72 Mon Sep 17 00:00:00 2001 From: Luca Abeni Date: Thu, 18 May 2017 22:13:31 +0200 Subject: [PATCH] sched/deadline: Implement GRUB accounting According to the GRUB (Greedy Reclaimation of Unused Bandwidth) reclaiming algorithm, the runtime is not decreased as "dq = -dt", but as "dq = -Uact dt" (where Uact is the per-runqueue active utilization). Hence, this commit modifies the runtime accounting rule in update_curr_dl() to implement the GRUB rule. Tested-by: Daniel Bristot de Oliveira Signed-off-by: Luca Abeni Signed-off-by: Peter Zijlstra (Intel) Cc: Claudio Scordino Cc: Joel Fernandes Cc: Juri Lelli Cc: Linus Torvalds Cc: Mathieu Poirier Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Tommaso Cucinotta Link: http://lkml.kernel.org/r/1495138417-6203-5-git-send-email-luca.abeni@santannapisa.it Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 4 ++-- kernel/sched/deadline.c | 17 +++++++++++++++++ kernel/sched/sched.h | 2 ++ 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 126339daebd7..b68a1fa05244 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2423,7 +2423,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) unsigned long to_ratio(u64 period, u64 runtime) { if (runtime == RUNTIME_INF) - return 1ULL << 20; + return BW_UNIT; /* * Doing this here saves a lot of checks in all @@ -2433,7 +2433,7 @@ unsigned long to_ratio(u64 period, u64 runtime) if (period == 0) return 0; - return div64_u64(runtime << 20, period); + return div64_u64(runtime << BW_SHIFT, period); } #ifdef CONFIG_SMP diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index add9cba1253c..0bee537554f6 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -917,6 +917,22 @@ int dl_runtime_exceeded(struct sched_dl_entity *dl_se) extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq); +/* + * This function implements the GRUB accounting rule: + * according to the GRUB reclaiming algorithm, the runtime is + * not decreased as "dq = -dt", but as "dq = -Uact dt", where + * Uact is the (per-runqueue) active utilization. + * Since rq->dl.running_bw contains Uact * 2^BW_SHIFT, the result + * has to be shifted right by BW_SHIFT. + */ +u64 grub_reclaim(u64 delta, struct rq *rq) +{ + delta *= rq->dl.running_bw; + delta >>= BW_SHIFT; + + return delta; +} + /* * Update the current task's runtime statistics (provided it is still * a -deadline task and has not been removed from the dl_rq). @@ -959,6 +975,7 @@ static void update_curr_dl(struct rq *rq) sched_rt_avg_update(rq, delta_exec); + delta_exec = grub_reclaim(delta_exec, rq); dl_se->runtime -= delta_exec; throttle: diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c58f38905e0a..bb409ef40120 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1496,6 +1496,8 @@ extern void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime extern void init_dl_task_timer(struct sched_dl_entity *dl_se); extern void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se); +#define BW_SHIFT 20 +#define BW_UNIT (1 << BW_SHIFT) unsigned long to_ratio(u64 period, u64 runtime); extern void init_entity_runnable_average(struct sched_entity *se); -- 2.39.5