From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 007EA2C840; Mon, 4 Mar 2024 20:17:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709583449; cv=none; b=H9skxixbhDi04ii4VhbAu21gxaTSGd4GrzUYU51ioU8m7BT9oSOi1zOzU2w7w06ImbErxuZ5ocrAQSs0c13AEulkB8RBkwwzKJwdRSb2odpq670sY42c8FO7jYcZf/SfZ4tum02XUG8RahEtv4INSV8GVm3PaClPy7GYoFOEbVs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709583449; c=relaxed/simple; bh=clDidIhiTcDaNyPWQCdL6Rs1LruWiA738NpcAJs2/80=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=fgNLZu8K7xoGjYp/tflv6lZkmF24UHRtcmOXv7yglnIcT2xzOW8yBU23blOtOqvVqfZzzAdsa4zjj+KfQGu+YqHAmgK7Y9iujimwd3o2MPv+yJEi0bco1OeABPPMVIFkBSD4lsQn0DTQ+RZP7UJWShe9/X4ZUdLcXlidjWgLnok= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 41B2C1576; Mon, 4 Mar 2024 12:17:54 -0800 (PST) Received: from e133047.arm.com (unknown [10.57.95.7]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C84B13F738; Mon, 4 Mar 2024 12:17:13 -0800 (PST) From: Christian Loehle To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, juri.lelli@redhat.com, mingo@redhat.com, rafael@kernel.org, dietmar.eggemann@arm.com, vschneid@redhat.com, vincent.guittot@linaro.org, Johannes.Thumshirn@wdc.com, adrian.hunter@intel.com, ulf.hansson@linaro.org, andres@anarazel.de, asml.silence@gmail.com, linux-pm@vger.kernel.org, linux-block@vger.kernel.org, io-uring@vger.kernel.org, Christian Loehle Subject: [RFC PATCH 2/2] cpufreq/schedutil: Remove iowait boost Date: Mon, 4 Mar 2024 20:16:25 +0000 Message-Id: <20240304201625.100619-3-christian.loehle@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240304201625.100619-1-christian.loehle@arm.com> References: <20240304201625.100619-1-christian.loehle@arm.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The previous commit provides a new cpu_util_cfs_boost_io interface for schedutil which uses the io boosted utilization of the per-task tracking strategy. Schedutil iowait boosting is therefore no longer necessary so remove it. Signed-off-by: Christian Loehle --- kernel/sched/cpufreq_schedutil.c | 152 +------------------------------ 1 file changed, 5 insertions(+), 147 deletions(-) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index cd0ca3cbd212..ed9fc88a74fc 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -6,8 +6,6 @@ * Author: Rafael J. Wysocki */ -#define IOWAIT_BOOST_MIN (SCHED_CAPACITY_SCALE / 8) - struct sugov_tunables { struct gov_attr_set attr_set; unsigned int rate_limit_us; @@ -42,10 +40,6 @@ struct sugov_cpu { struct sugov_policy *sg_policy; unsigned int cpu; - bool iowait_boost_pending; - unsigned int iowait_boost; - u64 last_update; - unsigned long util; unsigned long bw_min; @@ -195,141 +189,17 @@ unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual, return max(min, max); } -static void sugov_get_util(struct sugov_cpu *sg_cpu, unsigned long boost) +static void sugov_get_util(struct sugov_cpu *sg_cpu) { unsigned long min, max, util = cpu_util_cfs_boost(sg_cpu->cpu); unsigned long io_boost = cpu_util_io_boost(sg_cpu->cpu); - /* - * XXX: This already includes io boost now, makes little sense with - * sugov iowait boost on top - */ util = max(util, io_boost); util = effective_cpu_util(sg_cpu->cpu, util, &min, &max); - util = max(util, boost); sg_cpu->bw_min = min; sg_cpu->util = sugov_effective_cpu_perf(sg_cpu->cpu, util, min, max); } -/** - * sugov_iowait_reset() - Reset the IO boost status of a CPU. - * @sg_cpu: the sugov data for the CPU to boost - * @time: the update time from the caller - * @set_iowait_boost: true if an IO boost has been requested - * - * The IO wait boost of a task is disabled after a tick since the last update - * of a CPU. If a new IO wait boost is requested after more then a tick, then - * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy - * efficiency by ignoring sporadic wakeups from IO. - */ -static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time, - bool set_iowait_boost) -{ - s64 delta_ns = time - sg_cpu->last_update; - - /* Reset boost only if a tick has elapsed since last request */ - if (delta_ns <= TICK_NSEC) - return false; - - sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0; - sg_cpu->iowait_boost_pending = set_iowait_boost; - - return true; -} - -/** - * sugov_iowait_boost() - Updates the IO boost status of a CPU. - * @sg_cpu: the sugov data for the CPU to boost - * @time: the update time from the caller - * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait - * - * Each time a task wakes up after an IO operation, the CPU utilization can be - * boosted to a certain utilization which doubles at each "frequent and - * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization - * of the maximum OPP. - * - * To keep doubling, an IO boost has to be requested at least once per tick, - * otherwise we restart from the utilization of the minimum OPP. - */ -static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, - unsigned int flags) -{ - bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT; - - /* Reset boost if the CPU appears to have been idle enough */ - if (sg_cpu->iowait_boost && - sugov_iowait_reset(sg_cpu, time, set_iowait_boost)) - return; - - /* Boost only tasks waking up after IO */ - if (!set_iowait_boost) - return; - - /* Ensure boost doubles only one time at each request */ - if (sg_cpu->iowait_boost_pending) - return; - sg_cpu->iowait_boost_pending = true; - - /* Double the boost at each request */ - if (sg_cpu->iowait_boost) { - sg_cpu->iowait_boost = - min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE); - return; - } - - /* First wakeup after IO: start with minimum boost */ - sg_cpu->iowait_boost = IOWAIT_BOOST_MIN; -} - -/** - * sugov_iowait_apply() - Apply the IO boost to a CPU. - * @sg_cpu: the sugov data for the cpu to boost - * @time: the update time from the caller - * @max_cap: the max CPU capacity - * - * A CPU running a task which woken up after an IO operation can have its - * utilization boosted to speed up the completion of those IO operations. - * The IO boost value is increased each time a task wakes up from IO, in - * sugov_iowait_apply(), and it's instead decreased by this function, - * each time an increase has not been requested (!iowait_boost_pending). - * - * A CPU which also appears to have been idle for at least one tick has also - * its IO boost utilization reset. - * - * This mechanism is designed to boost high frequently IO waiting tasks, while - * being more conservative on tasks which does sporadic IO operations. - */ -static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time, - unsigned long max_cap) -{ - /* No boost currently required */ - if (!sg_cpu->iowait_boost) - return 0; - - /* Reset boost if the CPU appears to have been idle enough */ - if (sugov_iowait_reset(sg_cpu, time, false)) - return 0; - - if (!sg_cpu->iowait_boost_pending) { - /* - * No boost pending; reduce the boost value. - */ - sg_cpu->iowait_boost >>= 1; - if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) { - sg_cpu->iowait_boost = 0; - return 0; - } - } - - sg_cpu->iowait_boost_pending = false; - - /* - * sg_cpu->util is already in capacity scale; convert iowait_boost - * into the same scale so we can compare. - */ - return (sg_cpu->iowait_boost * max_cap) >> SCHED_CAPACITY_SHIFT; -} - #ifdef CONFIG_NO_HZ_COMMON static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { @@ -357,18 +227,12 @@ static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu, u64 time, unsigned long max_cap, unsigned int flags) { - unsigned long boost; - - sugov_iowait_boost(sg_cpu, time, flags); - sg_cpu->last_update = time; - ignore_dl_rate_limit(sg_cpu); if (!sugov_should_update_freq(sg_cpu->sg_policy, time)) return false; - boost = sugov_iowait_apply(sg_cpu, time, max_cap); - sugov_get_util(sg_cpu, boost); + sugov_get_util(sg_cpu); return true; } @@ -458,7 +322,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time, sg_cpu->sg_policy->last_freq_update_time = time; } -static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time) +static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu) { struct sugov_policy *sg_policy = sg_cpu->sg_policy; struct cpufreq_policy *policy = sg_policy->policy; @@ -469,11 +333,8 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time) for_each_cpu(j, policy->cpus) { struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j); - unsigned long boost; - - boost = sugov_iowait_apply(j_sg_cpu, time, max_cap); - sugov_get_util(j_sg_cpu, boost); + sugov_get_util(j_sg_cpu); util = max(j_sg_cpu->util, util); } @@ -489,13 +350,10 @@ sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags) raw_spin_lock(&sg_policy->update_lock); - sugov_iowait_boost(sg_cpu, time, flags); - sg_cpu->last_update = time; - ignore_dl_rate_limit(sg_cpu); if (sugov_should_update_freq(sg_policy, time)) { - next_f = sugov_next_freq_shared(sg_cpu, time); + next_f = sugov_next_freq_shared(sg_cpu); if (!sugov_update_next_freq(sg_policy, time, next_f)) goto unlock; -- 2.34.1