From: Vincent Guittot <vincent.guittot@linaro.org> To: Tim Chen <tim.c.chen@linux.intel.com> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, Russell King - ARM Linux <linux@arm.linux.org.uk>, LAK <linux-arm-kernel@lists.infradead.org>, Rik van Riel <riel@redhat.com>, Morten Rasmussen <Morten.Rasmussen@arm.com>, Mike Galbraith <efault@gmx.de>, Nicolas Pitre <nicolas.pitre@linaro.org>, "linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, Dietmar Eggemann <dietmar.eggemann@arm.com> Subject: Re: [PATCH v5 03/12] sched: fix avg_load computation Date: Thu, 4 Sep 2014 09:17:47 +0200 [thread overview] Message-ID: <CAKfTPtCd02JLyd335WUpU5RRUYmS=Ni9S0U_U1uDsYjs59oQ1A@mail.gmail.com> (raw) In-Reply-To: <1409787800.31585.26.camel@schen9-desk2.jf.intel.com> On 4 September 2014 01:43, Tim Chen <tim.c.chen@linux.intel.com> wrote: > On Wed, 2014-09-03 at 13:09 +0200, Vincent Guittot wrote: >> On 30 August 2014 14:00, Preeti U Murthy <preeti@linux.vnet.ibm.com> wrote: >> > Hi Vincent, >> > >> > On 08/26/2014 04:36 PM, Vincent Guittot wrote: >> >> The computation of avg_load and avg_load_per_task should only takes into >> >> account the number of cfs tasks. The non cfs task are already taken into >> >> account by decreasing the cpu's capacity and they will be tracked in the >> >> CPU's utilization (group_utilization) of the next patches >> >> >> >> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> >> >> --- >> >> kernel/sched/fair.c | 4 ++-- >> >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> >> index 87b9dc7..b85e9f7 100644 >> >> --- a/kernel/sched/fair.c >> >> +++ b/kernel/sched/fair.c >> >> @@ -4092,7 +4092,7 @@ static unsigned long capacity_of(int cpu) >> >> static unsigned long cpu_avg_load_per_task(int cpu) >> >> { >> >> struct rq *rq = cpu_rq(cpu); >> >> - unsigned long nr_running = ACCESS_ONCE(rq->nr_running); >> >> + unsigned long nr_running = ACCESS_ONCE(rq->cfs.h_nr_running); >> >> unsigned long load_avg = rq->cfs.runnable_load_avg; >> >> >> >> if (nr_running) >> >> @@ -5985,7 +5985,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, >> >> load = source_load(i, load_idx); >> >> >> >> sgs->group_load += load; >> >> - sgs->sum_nr_running += rq->nr_running; >> >> + sgs->sum_nr_running += rq->cfs.h_nr_running; >> >> >> >> if (rq->nr_running > 1) >> >> *overload = true; >> >> >> > >> > Why do we probe rq->nr_running while we do load balancing? Should not we >> > be probing cfs_rq->nr_running instead? We are interested after all in >> > load balancing fair tasks right? The reason I ask this is, I was >> > wondering if we need to make the above similar change in more places in >> > load balancing. >> >> Hi Preeti, >> >> Yes, we should probably the test rq->cfs.h_nr_running > 0 before >> setting overload. >> > > The overload indicator is used for knowing when we can totally avoid > load balancing to a cpu that is about to go idle. > We can avoid load balancing when no cpu has more than 1 task. So if you > have say just one fair task and multiple deadline tasks on a cpu, > and another cpu about to go idle, you should turn on normal load > balancing in the idle path by setting overload to true. The newly idle load balancing can only affect CFS tasks so triggering a load_balance because a cpu is overloaded by rt tasks only, will not change anything. > > So setting overload should be set based on rq->nr_running and not on > rq->cfs.h_nr_running. We should probably use both values like below if ((rq->nr_running > 1) && ( rq->cfs.h_nr_running > 0)) Regards, Vincent > > Thanks. > > Tim > >
WARNING: multiple messages have this Message-ID (diff)
From: vincent.guittot@linaro.org (Vincent Guittot) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v5 03/12] sched: fix avg_load computation Date: Thu, 4 Sep 2014 09:17:47 +0200 [thread overview] Message-ID: <CAKfTPtCd02JLyd335WUpU5RRUYmS=Ni9S0U_U1uDsYjs59oQ1A@mail.gmail.com> (raw) In-Reply-To: <1409787800.31585.26.camel@schen9-desk2.jf.intel.com> On 4 September 2014 01:43, Tim Chen <tim.c.chen@linux.intel.com> wrote: > On Wed, 2014-09-03 at 13:09 +0200, Vincent Guittot wrote: >> On 30 August 2014 14:00, Preeti U Murthy <preeti@linux.vnet.ibm.com> wrote: >> > Hi Vincent, >> > >> > On 08/26/2014 04:36 PM, Vincent Guittot wrote: >> >> The computation of avg_load and avg_load_per_task should only takes into >> >> account the number of cfs tasks. The non cfs task are already taken into >> >> account by decreasing the cpu's capacity and they will be tracked in the >> >> CPU's utilization (group_utilization) of the next patches >> >> >> >> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> >> >> --- >> >> kernel/sched/fair.c | 4 ++-- >> >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> >> index 87b9dc7..b85e9f7 100644 >> >> --- a/kernel/sched/fair.c >> >> +++ b/kernel/sched/fair.c >> >> @@ -4092,7 +4092,7 @@ static unsigned long capacity_of(int cpu) >> >> static unsigned long cpu_avg_load_per_task(int cpu) >> >> { >> >> struct rq *rq = cpu_rq(cpu); >> >> - unsigned long nr_running = ACCESS_ONCE(rq->nr_running); >> >> + unsigned long nr_running = ACCESS_ONCE(rq->cfs.h_nr_running); >> >> unsigned long load_avg = rq->cfs.runnable_load_avg; >> >> >> >> if (nr_running) >> >> @@ -5985,7 +5985,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, >> >> load = source_load(i, load_idx); >> >> >> >> sgs->group_load += load; >> >> - sgs->sum_nr_running += rq->nr_running; >> >> + sgs->sum_nr_running += rq->cfs.h_nr_running; >> >> >> >> if (rq->nr_running > 1) >> >> *overload = true; >> >> >> > >> > Why do we probe rq->nr_running while we do load balancing? Should not we >> > be probing cfs_rq->nr_running instead? We are interested after all in >> > load balancing fair tasks right? The reason I ask this is, I was >> > wondering if we need to make the above similar change in more places in >> > load balancing. >> >> Hi Preeti, >> >> Yes, we should probably the test rq->cfs.h_nr_running > 0 before >> setting overload. >> > > The overload indicator is used for knowing when we can totally avoid > load balancing to a cpu that is about to go idle. > We can avoid load balancing when no cpu has more than 1 task. So if you > have say just one fair task and multiple deadline tasks on a cpu, > and another cpu about to go idle, you should turn on normal load > balancing in the idle path by setting overload to true. The newly idle load balancing can only affect CFS tasks so triggering a load_balance because a cpu is overloaded by rt tasks only, will not change anything. > > So setting overload should be set based on rq->nr_running and not on > rq->cfs.h_nr_running. We should probably use both values like below if ((rq->nr_running > 1) && ( rq->cfs.h_nr_running > 0)) Regards, Vincent > > Thanks. > > Tim > >
next prev parent reply other threads:[~2014-09-04 7:18 UTC|newest] Thread overview: 164+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-08-26 11:06 [PATCH v5 00/12] sched: consolidation of cpu_capacity Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 01/12] sched: fix imbalance flag reset Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-09-19 11:47 ` [tip:sched/core] sched: Fix " tip-bot for Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 02/12] sched: remove a wake_affine condition Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-09-19 11:47 ` [tip:sched/core] sched: Remove a wake_affine() condition tip-bot for Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 03/12] sched: fix avg_load computation Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-08-30 12:00 ` Preeti U Murthy 2014-08-30 12:00 ` Preeti U Murthy 2014-09-03 11:09 ` Vincent Guittot 2014-09-03 11:09 ` Vincent Guittot 2014-09-03 23:43 ` Tim Chen 2014-09-03 23:43 ` Tim Chen 2014-09-04 7:17 ` Vincent Guittot [this message] 2014-09-04 7:17 ` Vincent Guittot 2014-09-04 16:26 ` Tim Chen 2014-09-04 16:26 ` Tim Chen 2014-09-05 11:10 ` Preeti U Murthy 2014-09-05 11:10 ` Preeti U Murthy 2014-09-19 11:47 ` [tip:sched/core] sched: Fix " tip-bot for Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 04/12] sched: Allow all archs to set the capacity_orig Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-08-27 13:12 ` Kamalesh Babulal 2014-08-27 13:12 ` Kamalesh Babulal 2014-08-30 17:07 ` Preeti U Murthy 2014-08-30 17:07 ` Preeti U Murthy 2014-09-01 8:05 ` Vincent Guittot 2014-09-01 8:05 ` Vincent Guittot 2014-09-03 8:41 ` Preeti U Murthy 2014-09-03 8:41 ` Preeti U Murthy 2014-09-10 13:50 ` Peter Zijlstra 2014-09-10 13:50 ` Peter Zijlstra 2014-09-10 14:22 ` Vincent Guittot 2014-09-10 14:22 ` Vincent Guittot 2014-09-11 10:36 ` Preeti U Murthy 2014-09-11 10:36 ` Preeti U Murthy 2014-09-19 11:47 ` [tip:sched/core] sched: Allow all architectures to set ' capacity_orig' tip-bot for Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 05/12] ARM: topology: use new cpu_capacity interface Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-09-11 18:52 ` Nicolas Pitre 2014-09-11 18:52 ` Nicolas Pitre 2014-09-19 11:48 ` [tip:sched/core] ARM: topology: Use the " tip-bot for Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 06/12] sched: add per rq cpu_capacity_orig Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-08-27 13:32 ` Kamalesh Babulal 2014-08-27 13:32 ` Kamalesh Babulal 2014-08-28 7:34 ` Vincent Guittot 2014-08-28 7:34 ` Vincent Guittot 2014-09-10 13:53 ` Peter Zijlstra 2014-09-10 13:53 ` Peter Zijlstra 2014-09-10 14:19 ` Vincent Guittot 2014-09-10 14:19 ` Vincent Guittot 2014-09-11 19:02 ` Nicolas Pitre 2014-09-11 19:02 ` Nicolas Pitre 2014-09-15 21:22 ` Vincent Guittot 2014-09-15 21:22 ` Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 07/12] sched: test the cpu's capacity in wake affine Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-09-10 14:19 ` Peter Zijlstra 2014-09-10 14:19 ` Peter Zijlstra 2014-09-19 11:48 ` [tip:sched/core] sched: Test the CPU's capacity in wake_affine() tip-bot for Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 08/12] sched: move cfs task on a CPU with higher capacity Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-08-30 17:50 ` Preeti U Murthy 2014-08-30 17:50 ` Preeti U Murthy 2014-09-01 8:45 ` Vincent Guittot 2014-09-01 8:45 ` Vincent Guittot 2014-09-03 9:11 ` Preeti U Murthy 2014-09-03 9:11 ` Preeti U Murthy 2014-09-03 11:44 ` Vincent Guittot 2014-09-03 11:44 ` Vincent Guittot 2014-09-03 12:26 ` Preeti U Murthy 2014-09-03 12:26 ` Preeti U Murthy 2014-09-03 12:49 ` Vincent Guittot 2014-09-03 12:49 ` Vincent Guittot 2014-09-11 9:27 ` Peter Zijlstra 2014-09-11 9:27 ` Peter Zijlstra 2014-09-05 12:06 ` Preeti U Murthy 2014-09-05 12:06 ` Preeti U Murthy 2014-09-05 12:24 ` Vincent Guittot 2014-09-05 12:24 ` Vincent Guittot 2014-09-11 10:07 ` Peter Zijlstra 2014-09-11 10:07 ` Peter Zijlstra 2014-09-11 11:20 ` Vincent Guittot 2014-09-11 11:20 ` Vincent Guittot 2014-09-11 10:13 ` Peter Zijlstra 2014-09-11 10:13 ` Peter Zijlstra 2014-09-11 12:14 ` Vincent Guittot 2014-09-11 12:14 ` Vincent Guittot 2014-09-11 11:54 ` Peter Zijlstra 2014-09-11 11:54 ` Peter Zijlstra 2014-08-26 11:06 ` [PATCH v5 09/12] sched: add usage_load_avg Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-09-04 7:34 ` [PATCH v5 09/11] " Vincent Guittot 2014-09-04 7:34 ` Vincent Guittot 2014-09-11 11:17 ` Peter Zijlstra 2014-09-11 11:17 ` Peter Zijlstra 2014-09-11 11:17 ` [PATCH v5 09/12] " Peter Zijlstra 2014-09-11 11:17 ` Peter Zijlstra 2014-09-11 12:18 ` Vincent Guittot 2014-09-11 12:18 ` Vincent Guittot 2014-09-11 12:20 ` Vincent Guittot 2014-09-11 12:20 ` Vincent Guittot 2014-09-15 19:15 ` Morten Rasmussen 2014-09-15 19:15 ` Morten Rasmussen 2014-09-15 22:33 ` Vincent Guittot 2014-09-15 22:33 ` Vincent Guittot 2014-08-26 11:06 ` [PATCH v5 10/12] sched: get CPU's utilization statistic Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-09-11 12:34 ` Peter Zijlstra 2014-09-11 12:34 ` Peter Zijlstra 2014-09-11 13:07 ` Vincent Guittot 2014-09-11 13:07 ` Vincent Guittot 2014-09-11 14:04 ` Peter Zijlstra 2014-09-11 14:04 ` Peter Zijlstra 2014-09-11 19:17 ` Nicolas Pitre 2014-09-11 19:17 ` Nicolas Pitre 2014-09-12 7:41 ` Vincent Guittot 2014-09-12 7:41 ` Vincent Guittot 2014-09-15 19:45 ` Morten Rasmussen 2014-09-15 19:45 ` Morten Rasmussen 2014-09-16 22:43 ` Vincent Guittot 2014-09-16 22:43 ` Vincent Guittot 2014-09-15 19:28 ` Morten Rasmussen 2014-09-15 19:28 ` Morten Rasmussen 2014-08-26 11:06 ` [PATCH v5 11/12] sched: replace capacity_factor by utilization Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot 2014-09-11 15:39 ` Peter Zijlstra 2014-09-11 15:39 ` Peter Zijlstra 2014-09-11 16:15 ` Peter Zijlstra 2014-09-11 16:15 ` Peter Zijlstra 2014-09-11 17:26 ` Vincent Guittot 2014-09-11 17:26 ` Vincent Guittot 2014-09-14 19:41 ` Peter Zijlstra 2014-09-14 19:41 ` Peter Zijlstra 2014-09-14 19:51 ` Peter Zijlstra 2014-09-14 19:51 ` Peter Zijlstra 2014-09-15 11:42 ` Peter Zijlstra 2014-09-15 11:42 ` Peter Zijlstra 2014-09-15 19:07 ` Nicolas Pitre 2014-09-15 19:07 ` Nicolas Pitre 2014-09-15 20:01 ` Peter Zijlstra 2014-09-15 20:01 ` Peter Zijlstra 2014-09-17 18:45 ` Morten Rasmussen 2014-09-17 18:45 ` Morten Rasmussen 2014-09-17 18:58 ` Morten Rasmussen 2014-09-17 18:58 ` Morten Rasmussen 2014-09-17 23:03 ` Peter Zijlstra 2014-09-17 23:03 ` Peter Zijlstra 2014-09-15 22:14 ` Vincent Guittot 2014-09-15 22:14 ` Vincent Guittot 2014-09-15 22:18 ` Vincent Guittot 2014-09-15 22:18 ` Vincent Guittot 2014-09-17 22:25 ` Peter Zijlstra 2014-09-17 22:25 ` Peter Zijlstra 2014-09-18 1:32 ` Vincent Guittot 2014-09-18 1:32 ` Vincent Guittot 2014-09-16 17:00 ` Dietmar Eggemann 2014-09-16 17:00 ` Dietmar Eggemann 2014-08-26 11:06 ` [PATCH v5 12/12] sched: add SD_PREFER_SIBLING for SMT level Vincent Guittot 2014-08-26 11:06 ` Vincent Guittot
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