Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751223AbWAZBJ5 (ORCPT ); Wed, 25 Jan 2006 20:09:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751208AbWAZBJ5 (ORCPT ); Wed, 25 Jan 2006 20:09:57 -0500 Received: from omta04ps.mx.bigpond.com ([144.140.83.156]:16106 "EHLO omta04ps.mx.bigpond.com") by vger.kernel.org with ESMTP id S1751223AbWAZBJ4 (ORCPT ); Wed, 25 Jan 2006 20:09:56 -0500 Message-ID: <43D82161.6000809@bigpond.net.au> Date: Thu, 26 Jan 2006 12:09:53 +1100 From: Peter Williams User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Paolo Ornati CC: Linux Kernel Mailing List , Chris Han , Con Kolivas , William Lee Irwin III , Jake Moilanen Subject: Re: [ANNOUNCE][RFC] PlugSched-6.2 for 2.6.16-rc1 and 2.6.16-rc1-mm1 References: <43D00887.6010409@bigpond.net.au> <20060121114616.4a906b4f@localhost> <43D2BE83.1020200@bigpond.net.au> <43D40B96.3060705@bigpond.net.au> <43D4281D.10009@bigpond.net.au> <20060123212158.3fba71d5@localhost> In-Reply-To: <20060123212158.3fba71d5@localhost> Content-Type: multipart/mixed; boundary="------------070908010708010307030903" X-Authentication-Info: Submitted using SMTP AUTH PLAIN at omta04ps.mx.bigpond.com from [147.10.133.38] using ID pwil3058@bigpond.net.au at Thu, 26 Jan 2006 01:09:53 +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10114 Lines: 294 This is a multi-part message in MIME format. --------------070908010708010307030903 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Paolo Ornati wrote: > On Mon, 23 Jan 2006 11:49:33 +1100 > Peter Williams wrote: > > >>>However, in spite of the above, the fairness mechanism should have been >>>able to generate enough bonus points to get dd's priority back to less >>>than 34. I'm still investigating why this didn't happen. >> >>Problem solved. It was a scaling issue during the calculation of >>expected delay. The attached patch should fix both the CPU hog problem >>and the fairness problem. Could you give it a try? >> > > > Mmmm... it doesn't work: > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 5516 paolo 34 0 115m 18m 2432 S 87.5 3.7 0:23.72 transcode > 5530 paolo 34 0 51000 4472 1872 S 8.0 0.9 0:02.29 tcdecode > 5523 paolo 34 0 19840 1088 880 R 2.0 0.2 0:00.21 tcdemux > 5522 paolo 34 0 22156 1204 972 R 0.7 0.2 0:00.02 tccat > 5539 paolo 34 0 4952 1468 372 D 0.7 0.3 0:00.04 dd > 5350 root 28 0 167m 16m 3228 S 0.3 3.4 0:03.64 X > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 5456 paolo 34 0 115m 18m 2432 D 63.9 3.7 0:48.21 transcode > 5470 paolo 37 0 50996 4472 1872 R 6.2 0.9 0:05.20 tcdecode > 5493 paolo 34 0 4952 1472 372 R 1.5 0.3 0:00.22 dd > 5441 paolo 28 0 86656 21m 15m S 0.2 4.4 0:00.77 konsole > 5468 paolo 34 0 19840 1088 880 S 0.2 0.2 0:00.23 tcdemux > I know that I've said this before but I've found the problem. Embarrassingly, it was a basic book keeping error (recently introduced and equivalent to getting nr_running wrong for each CPU) in the gathering of the statistics that I use. :-( The attached patch (applied on top of the PlugSched patch) should fix things. Could you test it please? Thanks Peter -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce --------------070908010708010307030903 Content-Type: text/plain; name="fix-spa_ws-scheduler-v2" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="fix-spa_ws-scheduler-v2" Index: MM-2.6.16/kernel/sched_spa_ws.c =================================================================== --- MM-2.6.16.orig/kernel/sched_spa_ws.c 2006-01-21 16:42:45.000000000 +1100 +++ MM-2.6.16/kernel/sched_spa_ws.c 2006-01-26 11:44:14.000000000 +1100 @@ -44,7 +44,8 @@ static unsigned int initial_ia_bonus = D #define LSHARES_AVG_OFFSET 7 #define LSHARES_AVG_ALPHA ((1 << LSHARES_AVG_OFFSET) - 2) #define LSHARES_AVG_INCR(a) ((a) << 1) -#define LSHARES_AVG_ONE (1UL << LSHARES_AVG_OFFSET) +#define LSHARES_AVG_REAL(s) ((s) << LSHARES_AVG_OFFSET) +#define LSHARES_AVG_ONE LSAHRES_AVG_REAL(1UL) #define LSHARES_AVG_MUL(a, b) (((a) * (b)) >> LSHARES_AVG_OFFSET) static unsigned int max_fairness_bonus = DEF_MAX_FAIRNESS_BONUS; @@ -121,32 +122,9 @@ static inline void zero_interactive_bonu p->sdu.spa.interactive_bonus = 0; } -static inline int current_fairness_bonus(const struct task_struct *p) -{ - return p->sdu.spa.auxilary_bonus >> FAIRNESS_BONUS_OFFSET; -} - -static inline int current_fairness_bonus_rnd(const struct task_struct *p) -{ - return (p->sdu.spa.auxilary_bonus + (1UL << (FAIRNESS_BONUS_OFFSET - 1))) - >> FAIRNESS_BONUS_OFFSET; -} - -static inline void decr_fairness_bonus(struct task_struct *p) -{ - p->sdu.spa.auxilary_bonus *= ((1UL << FAIRNESS_BONUS_OFFSET) - 2); - p->sdu.spa.auxilary_bonus >>= FAIRNESS_BONUS_OFFSET; -} - -static inline void incr_fairness_bonus(struct task_struct *p) -{ - decr_fairness_bonus(p); - p->sdu.spa.auxilary_bonus += (max_fairness_bonus << 1); -} - static inline int bonuses(const struct task_struct *p) { - return current_ia_bonus_rnd(p) + current_fairness_bonus_rnd(p); + return current_ia_bonus_rnd(p) + p->sdu.spa.auxilary_bonus; } static int spa_ws_effective_prio(const struct task_struct *p) @@ -211,43 +189,37 @@ static inline unsigned int map_ratio(uns static void spa_ws_reassess_fairness_bonus(struct task_struct *p) { - unsigned long long expected_delay; + unsigned long long expected_delay, adjusted_delay; unsigned long long avg_lshares; + unsigned long pshares; -#if 0 p->sdu.spa.auxilary_bonus = 0; if (max_fairness_bonus == 0) return; -#endif + pshares = LSHARES_AVG_REAL(p->sdu.spa.eb_shares); avg_lshares = per_cpu(rq_avg_lshares, task_cpu(p)); - if (avg_lshares <= p->sdu.spa.eb_shares) + if (avg_lshares <= pshares) expected_delay = 0; else { - expected_delay = LSHARES_AVG_MUL(p->sdu.spa.avg_cpu_per_cycle, - (avg_lshares - p->sdu.spa.eb_shares)); - (void)do_div(expected_delay, p->sdu.spa.eb_shares); + expected_delay = p->sdu.spa.avg_cpu_per_cycle * + (avg_lshares - pshares); + (void)do_div(expected_delay, pshares); } -#if 1 - if (p->sdu.spa.avg_delay_per_cycle > expected_delay) - incr_fairness_bonus(p); - else - decr_fairness_bonus(p); -#else + /* * No delay means no bonus, but * NB this test also avoids a possible divide by zero error if * cpu is also zero and negative bonuses */ - lhs = p->sdu.spa.avg_delay_per_cycle; - if (lhs <= rhs) + if (p->sdu.spa.avg_delay_per_cycle <= expected_delay) return; - lhs -= rhs; + adjusted_delay = p->sdu.spa.avg_delay_per_cycle - expected_delay; p->sdu.spa.auxilary_bonus = - map_ratio(lhs, lhs + p->sdu.spa.avg_cpu_per_cycle, + map_ratio(adjusted_delay, + adjusted_delay + p->sdu.spa.avg_cpu_per_cycle, max_fairness_bonus); -#endif } static inline int spa_ws_eligible(struct task_struct *p) @@ -255,6 +227,15 @@ static inline int spa_ws_eligible(struct return p->sdu.spa.avg_sleep_per_cycle < WS_BIG_SLEEP; } +static inline int spa_sleepiness_exceeds_ppt(const struct task_struct *p, + unsigned int ppt) +{ + return RATIO_EXCEEDS_PPT(p->sdu.spa.avg_sleep_per_cycle, + p->sdu.spa.avg_sleep_per_cycle + + p->sdu.spa.avg_cpu_per_cycle, + ppt); +} + static void spa_ws_reassess_at_activation(struct task_struct *p) { spa_ws_reassess_fairness_bonus(p); @@ -264,7 +245,7 @@ static void spa_ws_reassess_at_activatio else partial_incr_interactive_bonus(p); } - else if (!spa_ia_sleepiness_exceeds_ppt(p, iab_decr_threshold)) + else if (!spa_sleepiness_exceeds_ppt(p, iab_decr_threshold)) decr_interactive_bonus(p); else if (!spa_ia_sleepiness_exceeds_ppt(p, (iab_decr_threshold + iab_incr_threshold) / 2)) partial_decr_interactive_bonus(p); @@ -284,7 +265,7 @@ static void spa_ws_reassess_at_end_of_ts /* Don't punish tasks that have done a lot of sleeping for the * occasional run of short sleeps unless they become a cpu hog. */ - if (!spa_ia_sleepiness_exceeds_ppt(p, iab_decr_threshold)) + if (!spa_sleepiness_exceeds_ppt(p, iab_decr_threshold)) decr_interactive_bonus(p); else if (!spa_ia_sleepiness_exceeds_ppt(p, (iab_decr_threshold + iab_incr_threshold) / 2)) partial_decr_interactive_bonus(p); Index: MM-2.6.16/kernel/sched_spa.c =================================================================== --- MM-2.6.16.orig/kernel/sched_spa.c 2006-01-21 16:41:32.000000000 +1100 +++ MM-2.6.16/kernel/sched_spa.c 2006-01-26 11:43:20.000000000 +1100 @@ -490,18 +490,29 @@ static inline int effective_prio(const t return spa_sched_child->normal_effective_prio(p); } +static inline void spa_inc_nr_running(task_t *p, runqueue_t *rq) +{ + inc_nr_running(p, rq); + check_restart_promotions(rq); + if (!rt_task(p)) + rq->qu.spa.nr_active_eb_shares += p->sdu.spa.eb_shares; +} + +static inline void spa_dec_nr_running(task_t *p, runqueue_t *rq) +{ + dec_nr_running(p, rq); + check_stop_promotions(rq); + if (!rt_task(p)) + rq->qu.spa.nr_active_eb_shares -= p->sdu.spa.eb_shares; +} + /* * __activate_task - move a task to the runqueue. */ static inline void __activate_task(task_t *p, runqueue_t *rq) { - struct spa_runqueue_queue *rqq = &rq->qu.spa; - - enqueue_task(p, rqq); - inc_nr_running(p, rq); - check_restart_promotions(rq); - if (!rt_task(p)) - rqq->nr_active_eb_shares += p->sdu.spa.eb_shares; + enqueue_task(p, &rq->qu.spa); + spa_inc_nr_running(p, rq); } static inline void do_nothing_to_task(task_t *p) {} @@ -536,11 +547,8 @@ static inline void deactivate_task(struc { struct spa_runqueue_queue *rqq = &rq->qu.spa; - dec_nr_running(p, rq); + spa_dec_nr_running(p, rq); dequeue_task(p, rqq); - check_stop_promotions(rq); - if (!rt_task(p)) - rqq->nr_active_eb_shares -= p->sdu.spa.eb_shares; } /* @@ -648,7 +656,7 @@ void spa_wake_up_new_task(task_t * p, un } else { p->prio = current->prio; list_add_tail(&p->run_list, ¤t->run_list); - inc_nr_running(p, rq); + spa_inc_nr_running(p, rq); check_restart_promotions(rq); } set_need_resched(); @@ -678,13 +686,11 @@ static inline void pull_task(runqueue_t *src_rq, task_t *p, runqueue_t *this_rq, int this_cpu) { dequeue_task(p, &src_rq->qu.spa); - dec_nr_running(p, src_rq); - check_stop_promotions(src_rq); + spa_dec_nr_running(p, src_rq); set_task_cpu(p, this_cpu); adjust_timestamp(p, this_rq, src_rq); - inc_nr_running(p, this_rq); + spa_inc_nr_running(p, this_rq); enqueue_task(p, &this_rq->qu.spa); - check_restart_promotions(this_rq); preempt_if_warranted(p, this_rq); } @@ -1333,7 +1339,7 @@ void spa_set_select_idle_first(struct ru __setscheduler(rq->idle, SCHED_FIFO, MAX_RT_PRIO - 1); /* Add idle task to _front_ of it's priority queue */ enqueue_task_head(rq->idle, &rq->qu.spa); - inc_nr_running(rq->idle, rq); + spa_inc_nr_running(rq->idle, rq); } void spa_set_select_idle_last(struct runqueue *rq) --------------070908010708010307030903-- - 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/