From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Piel Subject: [PATCH][3/3] ondemand governor automatic downscaling Date: Wed, 11 May 2005 14:31:56 +0200 Message-ID: <4281FB3C.5090400@tremplin-utc.net> References: <200503140829.04750.lkml@kcore.org> <42354400.7070500@tremplin-utc.net> <20050511013334.GB8039@redhat.com> <20050511023448.GA25506@redhat.com> <4281F837.5070608@tremplin-utc.net> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------090903040809040100050304" Return-path: In-Reply-To: <4281F837.5070608@tremplin-utc.net> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@lists.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=m.gmane.org@lists.linux.org.uk To: Dave Jones Cc: cpufreq@zenii.linux.org.uk, linux@dominikbrodowski.net This is a multi-part message in MIME format. --------------090903040809040100050304 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit This patch has been redone for latest snapshot. Very little differences from before, use the usecs_to_jiffies() instead of the old sampling_rate_in_HZ() and comments updated. Eric -- Here is a new policy for the ondemand governor. The modification concerns the frequency downscaling. Instead of decreasing to a lower frequency when the CPU usage is under 20%, this new policy automatically scales to the optimal frequency. The optimal frequency being the lowest frequency which provides enough power to not trigger the upscaling policy. Signed-off-by: Eric Piel Signed-off-by: Venkatesh Pallipadi -- --------------090903040809040100050304 Content-Type: text/x-patch; name="ondemand-automatic-downscaling-2.6.11-20050511.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="ondemand-automatic-downscaling-2.6.11-20050511.patch" --- linux-2.6.11/drivers/cpufreq/cpufreq_ondemand.c.cpufreq-20050501-2 2005-05-11 13:32:14.000000000 +0200 +++ linux-2.6.11/drivers/cpufreq/cpufreq_ondemand.c 2005-05-11 14:06:06.000000000 +0200 @@ -34,13 +34,9 @@ */ #define DEF_FREQUENCY_UP_THRESHOLD (80) -#define MIN_FREQUENCY_UP_THRESHOLD (0) +#define MIN_FREQUENCY_UP_THRESHOLD (10) #define MAX_FREQUENCY_UP_THRESHOLD (100) -#define DEF_FREQUENCY_DOWN_THRESHOLD (20) -#define MIN_FREQUENCY_DOWN_THRESHOLD (0) -#define MAX_FREQUENCY_DOWN_THRESHOLD (100) - /* * The polling frequency of this governor depends on the capability of * the processor. Default polling frequency is 1000 times the transition @@ -77,12 +73,10 @@ struct dbs_tuners { unsigned int sampling_rate; unsigned int sampling_down_factor; unsigned int up_threshold; - unsigned int down_threshold; }; static struct dbs_tuners dbs_tuners_ins = { .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, - .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD, .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, }; @@ -114,7 +108,6 @@ static ssize_t show_##file_name \ show_one(sampling_rate, sampling_rate); show_one(sampling_down_factor, sampling_down_factor); show_one(up_threshold, up_threshold); -show_one(down_threshold, down_threshold); static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, const char *buf, size_t count) @@ -160,8 +153,7 @@ static ssize_t store_up_threshold(struct down(&dbs_sem); if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || - input < MIN_FREQUENCY_UP_THRESHOLD || - input <= dbs_tuners_ins.down_threshold) { + input < MIN_FREQUENCY_UP_THRESHOLD) { up(&dbs_sem); return -EINVAL; } @@ -172,26 +164,6 @@ static ssize_t store_up_threshold(struct return count; } -static ssize_t store_down_threshold(struct cpufreq_policy *unused, - const char *buf, size_t count) -{ - unsigned int input; - int ret; - ret = sscanf (buf, "%u", &input); - - down(&dbs_sem); - if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || - input < MIN_FREQUENCY_DOWN_THRESHOLD || - input >= dbs_tuners_ins.up_threshold) { - up(&dbs_sem); - return -EINVAL; - } - - dbs_tuners_ins.down_threshold = input; - up(&dbs_sem); - - return count; -} #define define_one_rw(_name) \ static struct freq_attr _name = \ @@ -200,7 +172,6 @@ __ATTR(_name, 0644, show_##_name, store_ define_one_rw(sampling_rate); define_one_rw(sampling_down_factor); define_one_rw(up_threshold); -define_one_rw(down_threshold); static struct attribute * dbs_attributes[] = { &sampling_rate_max.attr, @@ -208,7 +179,6 @@ static struct attribute * dbs_attributes &sampling_rate.attr, &sampling_down_factor.attr, &up_threshold.attr, - &down_threshold.attr, NULL }; @@ -221,8 +191,8 @@ static struct attribute_group dbs_attr_g static void dbs_check_cpu(int cpu) { - unsigned int idle_ticks, up_idle_ticks, down_idle_ticks; - unsigned int freq_down_step; + unsigned int idle_ticks, up_idle_ticks, total_ticks; + unsigned int freq_next; unsigned int freq_down_sampling_rate; static int down_skip[NR_CPUS]; struct cpu_dbs_info_s *this_dbs_info; @@ -240,13 +210,13 @@ static void dbs_check_cpu(int cpu) * Every sampling_rate, we check * - If current idle time is less than 20%, then we try to * increase frequency - * Every sampling_rate*sampling_down_factor, we check - * - If current idle time is more than 80%, then we try to - * decrease frequency + * Every sampling_rate*sampling_down_factor, we look for a the lowest + * frequency which can sustain the load while keeping idle time over + * 30%. If such a frequency exist, we try to decrease to this frequency. * * Any frequency increase takes it to the maximum frequency. - * Frequency reduction happens at minimum steps of - * 5% of max_frequency + * Frequency reduction happens at minimum steps of 5% of current + * frequency. */ /* Check for frequency increase */ @@ -289,7 +259,12 @@ static void dbs_check_cpu(int cpu) down_skip[cpu]++; if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor) return; + down_skip[cpu] = 0; + /* don't try to decrease the frequency if it's already the min */ + if (policy->cur == policy->min) + return; + idle_ticks = UINT_MAX; for_each_cpu_mask(j, policy->cpus) { unsigned int tmp_idle_ticks, total_idle_ticks; @@ -307,27 +282,21 @@ static void dbs_check_cpu(int cpu) idle_ticks = tmp_idle_ticks; } - /* Scale idle ticks by 100 and compare with up and down ticks */ - idle_ticks *= 100; - down_skip[cpu] = 0; - + /* Compute how many ticks there are between two measurements */ freq_down_sampling_rate = dbs_tuners_ins.sampling_rate * dbs_tuners_ins.sampling_down_factor; - down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) * - usecs_to_jiffies(freq_down_sampling_rate); - - if (idle_ticks > down_idle_ticks) { - freq_down_step = (5 * policy->max) / 100; - - /* max freq cannot be less than 100. But who knows.... */ - if (unlikely(freq_down_step == 0)) - freq_down_step = 5; - - __cpufreq_driver_target(policy, - policy->cur - freq_down_step, - CPUFREQ_RELATION_H); - return; - } + total_ticks = usecs_to_jiffies(freq_down_sampling_rate); + + /* + * The optimal frequency is the frequency that is the lowest that + * can support the current CPU usage without triggering + * the up policy. To be safe, we focus 10 points under the threshold. + */ + freq_next = ((total_ticks - idle_ticks) * 100) / total_ticks; + freq_next = (freq_next * policy->cur) / (dbs_tuners_ins.up_threshold - 10); + + if (freq_next <= ((policy->cur * 95) / 100)) + __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L); } static void do_dbs_timer(void *data) --------------090903040809040100050304 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Cpufreq mailing list Cpufreq@lists.linux.org.uk http://lists.linux.org.uk/mailman/listinfo/cpufreq --------------090903040809040100050304--