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[71.255.246.27]) by smtp.googlemail.com with ESMTPSA id 124sm13014259qko.11.2020.01.28.14.36.20 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 28 Jan 2020 14:36:21 -0800 (PST) From: Thara Gopinath To: mingo@redhat.com, peterz@infradead.org, ionela.voinescu@arm.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rui.zhang@intel.com, qperret@google.com, daniel.lezcano@linaro.org, viresh.kumar@linaro.org, rostedt@goodmis.org, will@kernel.org, catalin.marinas@arm.com, sudeep.holla@arm.com, juri.lelli@redhat.com, corbet@lwn.net Cc: linux-kernel@vger.kernel.org, amit.kachhap@gmail.com, javi.merino@kernel.org, amit.kucheria@verdurent.com Subject: [Patch v9 7/8] sched/fair: Enable tuning of decay period Date: Tue, 28 Jan 2020 17:36:06 -0500 Message-Id: <1580250967-4386-8-git-send-email-thara.gopinath@linaro.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1580250967-4386-1-git-send-email-thara.gopinath@linaro.org> References: <1580250967-4386-1-git-send-email-thara.gopinath@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thermal pressure follows pelt signals which means the decay period for thermal pressure is the default pelt decay period. Depending on soc characteristics and thermal activity, it might be beneficial to decay thermal pressure slower, but still in-tune with the pelt signals. One way to achieve this is to provide a command line parameter to set a decay shift parameter to an integer between 0 and 10. Signed-off-by: Thara Gopinath --- v8->v9: - Initialized the __shift to 0 in setup_sched_thermal_decay_shift as per Quentin's suggestion. Documentation/admin-guide/kernel-parameters.txt | 5 +++++ kernel/sched/core.c | 2 +- kernel/sched/fair.c | 15 ++++++++++++++- kernel/sched/sched.h | 18 ++++++++++++++++++ 4 files changed, 38 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index e35b28e..be4147b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4376,6 +4376,11 @@ incurs a small amount of overhead in the scheduler but is useful for debugging and performance tuning. + sched_thermal_decay_shift= + [KNL, SMP] Set decay shift for thermal pressure signal. + Format: integer between 0 and 10 + Default is 0. + skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate xtime_lock contention on larger systems, and/or RCU lock contention on all systems with CONFIG_MAXSMP set. diff --git a/kernel/sched/core.c b/kernel/sched/core.c index b921795..508e64b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3602,7 +3602,7 @@ void scheduler_tick(void) update_rq_clock(rq); thermal_pressure = arch_cpu_thermal_pressure(cpu_of(rq)); - update_thermal_load_avg(rq_clock_task(rq), rq, thermal_pressure); + update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure); curr->sched_class->task_tick(rq, curr, 0); calc_global_load_tick(rq); psi_task_tick(rq); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d879077..df23564 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -86,6 +86,19 @@ static unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; const_debug unsigned int sysctl_sched_migration_cost = 500000UL; +int sched_thermal_decay_shift; +static int __init setup_sched_thermal_decay_shift(char *str) +{ + int _shift = 0; + + if (kstrtoint(str, 0, &_shift)) + pr_warn("Unable to set scheduler thermal pressure decay shift parameter\n"); + + sched_thermal_decay_shift = clamp(_shift, 0, 10); + return 1; +} +__setup("sched_thermal_decay_shift=", setup_sched_thermal_decay_shift); + #ifdef CONFIG_SMP /* * For asym packing, by default the lower numbered CPU has higher priority. @@ -7530,7 +7543,7 @@ static bool __update_blocked_others(struct rq *rq, bool *done) decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) | update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) | - update_thermal_load_avg(rq_clock_task(rq), rq, thermal_pressure) | + update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) | update_irq_load_avg(rq, 0); if (others_have_blocked(rq)) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1f256cb..acd32bf 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1110,6 +1110,24 @@ static inline u64 rq_clock_task(struct rq *rq) return rq->clock_task; } +/** + * By default the decay is the default pelt decay period. + * The decay shift can change the decay period in + * multiples of 32. + * Decay shift Decay period(ms) + * 0 32 + * 1 64 + * 2 128 + * 3 256 + * 4 512 + */ +extern int sched_thermal_decay_shift; + +static inline u64 rq_clock_thermal(struct rq *rq) +{ + return rq_clock_task(rq) >> sched_thermal_decay_shift; +} + static inline void rq_clock_skip_update(struct rq *rq) { lockdep_assert_held(&rq->lock); -- 2.1.4