linaro-dev January 2013

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[PATCH] cpufreq: interactive: introduce hispeed2 for big LITTLE systems

by Viresh Kumar

Latest big LITTLE systems for ARM SoC's have following kind of ranges of freqs: LITTLE CPU ranges: x MHz -> y MHz big CPU ranges: y + delta -> z MHz For these, we use hispeed_freq as y MHz, to avoid a switch of clusters from LITTLE to big when load burst comes. Similar to non big.LITTLE systems, we also need to avoid highest OPPs for load bursts and so need another "speed breaker". Hence, we introduce hispeed2_freq here. This would normally be set to z - delta MHz. For, non big.LITTLE systems if we don't set hispeed2_freq, it would be set as policy->max frequency. And so, behavior would remain same as existing code. Based on Initial work from Sudeep, hence his SOB. Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha(a)arm.com> Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org> --- drivers/cpufreq/cpufreq_interactive.c | 119 +++++++++++++++++++++++++++++++--- 1 file changed, 111 insertions(+), 8 deletions(-) diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c index 4dc7f04..0c5bb2c 100644 --- a/drivers/cpufreq/cpufreq_interactive.c +++ b/drivers/cpufreq/cpufreq_interactive.c @@ -68,6 +68,13 @@ static unsigned int hispeed_freq; #define DEFAULT_GO_HISPEED_LOAD 85 static unsigned long go_hispeed_load; +/* Hi speed2 to bump to from Hi speed when load bursts over hispeed freq */ +static unsigned int hispeed2_freq; + +/* Go to hi speed2 when CPU load at or above this value. */ +#define DEFAULT_GO_HISPEED2_LOAD 95 +static unsigned long go_hispeed2_load; + /* Target load. Lower values result in higher CPU speeds. */ #define DEFAULT_TARGET_LOAD 90 static unsigned int default_target_loads[] = {DEFAULT_TARGET_LOAD}; @@ -88,12 +95,15 @@ static unsigned long min_sample_time; static unsigned long timer_rate; /* - * Wait this long before raising speed above hispeed, by default a single - * timer interval. + * Wait this long before raising speed above hispeed/hispeed2, by default a + * single timer interval. */ #define DEFAULT_ABOVE_HISPEED_DELAY DEFAULT_TIMER_RATE static unsigned long above_hispeed_delay_val; +#define DEFAULT_ABOVE_HISPEED2_DELAY DEFAULT_TIMER_RATE +static unsigned long above_hispeed2_delay_val; + /* Non-zero means indefinite speed boost active */ static int boost_val; /* Duration of a boot pulse in usecs */ @@ -272,7 +282,7 @@ static void cpufreq_interactive_timer(unsigned long data) int cpu_load; struct cpufreq_interactive_cpuinfo *pcpu = &per_cpu(cpuinfo, data); - unsigned int new_freq; + unsigned int new_freq = 0, min_freq = 0; unsigned int loadadjfreq; unsigned int index; unsigned long flags; @@ -301,13 +311,22 @@ static void cpufreq_interactive_timer(unsigned long data) if (pcpu->target_freq < hispeed_freq) { new_freq = hispeed_freq; } else { - new_freq = choose_freq(pcpu, loadadjfreq); - - if (new_freq < hispeed_freq) - new_freq = hispeed_freq; + if (cpu_load >= go_hispeed2_load) { + if (pcpu->target_freq < hispeed2_freq) + new_freq = hispeed2_freq; + else + min_freq = hispeed2_freq; + } else { + min_freq = hispeed_freq; + } } - } else { + } + + if (!new_freq) { new_freq = choose_freq(pcpu, loadadjfreq); + + if (new_freq < min_freq) + new_freq = min_freq; } if (pcpu->target_freq >= hispeed_freq && @@ -319,6 +338,15 @@ static void cpufreq_interactive_timer(unsigned long data) goto rearm; } + if (pcpu->target_freq >= hispeed2_freq && + new_freq > pcpu->target_freq && + now - pcpu->hispeed_validate_time < above_hispeed2_delay_val) { + trace_cpufreq_interactive_notyet( + data, cpu_load, pcpu->target_freq, + pcpu->policy->cur, new_freq); + goto rearm; + } + pcpu->hispeed_validate_time = now; if (cpufreq_frequency_table_target(pcpu->policy, pcpu->freq_table, @@ -688,6 +716,51 @@ static ssize_t store_go_hispeed_load(struct kobject *kobj, static struct global_attr go_hispeed_load_attr = __ATTR(go_hispeed_load, 0644, show_go_hispeed_load, store_go_hispeed_load); +static ssize_t show_hispeed2_freq(struct kobject *kobj, + struct attribute *attr, char *buf) +{ + return sprintf(buf, "%u\n", hispeed2_freq); +} + +static ssize_t store_hispeed2_freq(struct kobject *kobj, + struct attribute *attr, const char *buf, + size_t count) +{ + int ret; + long unsigned int val; + + ret = strict_strtoul(buf, 0, &val); + if (ret < 0) + return ret; + hispeed2_freq = val; + return count; +} + +static struct global_attr hispeed2_freq_attr = __ATTR(hispeed2_freq, 0644, + show_hispeed2_freq, store_hispeed2_freq); + +static ssize_t show_go_hispeed2_load(struct kobject *kobj, + struct attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", go_hispeed2_load); +} + +static ssize_t store_go_hispeed2_load(struct kobject *kobj, + struct attribute *attr, const char *buf, size_t count) +{ + int ret; + unsigned long val; + + ret = strict_strtoul(buf, 0, &val); + if (ret < 0) + return ret; + go_hispeed2_load = val; + return count; +} + +static struct global_attr go_hispeed2_load_attr = __ATTR(go_hispeed2_load, 0644, + show_go_hispeed2_load, store_go_hispeed2_load); + static ssize_t show_min_sample_time(struct kobject *kobj, struct attribute *attr, char *buf) { @@ -732,6 +805,28 @@ static ssize_t store_above_hispeed_delay(struct kobject *kobj, define_one_global_rw(above_hispeed_delay); +static ssize_t show_above_hispeed2_delay(struct kobject *kobj, + struct attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", above_hispeed2_delay_val); +} + +static ssize_t store_above_hispeed2_delay(struct kobject *kobj, + struct attribute *attr, + const char *buf, size_t count) +{ + int ret; + unsigned long val; + + ret = strict_strtoul(buf, 0, &val); + if (ret < 0) + return ret; + above_hispeed2_delay_val = val; + return count; +} + +define_one_global_rw(above_hispeed2_delay); + static ssize_t show_timer_rate(struct kobject *kobj, struct attribute *attr, char *buf) { @@ -854,6 +949,9 @@ static struct attribute *interactive_attributes[] = { &hispeed_freq_attr.attr, &go_hispeed_load_attr.attr, &above_hispeed_delay.attr, + &hispeed2_freq_attr.attr, + &go_hispeed2_load_attr.attr, + &above_hispeed2_delay.attr, &min_sample_time_attr.attr, &timer_rate_attr.attr, &timer_slack.attr, @@ -906,6 +1004,9 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy, if (!hispeed_freq) hispeed_freq = policy->max; + if (!hispeed2_freq || hispeed2_freq > policy->max) + hispeed2_freq = policy->max; + for_each_cpu(j, policy->cpus) { unsigned long expires; @@ -994,6 +1095,8 @@ static int __init cpufreq_interactive_init(void) go_hispeed_load = DEFAULT_GO_HISPEED_LOAD; min_sample_time = DEFAULT_MIN_SAMPLE_TIME; above_hispeed_delay_val = DEFAULT_ABOVE_HISPEED_DELAY; + go_hispeed2_load = DEFAULT_GO_HISPEED2_LOAD; + above_hispeed2_delay_val = DEFAULT_ABOVE_HISPEED2_DELAY; timer_rate = DEFAULT_TIMER_RATE; /* Initalize per-cpu timers */ -- 1.7.12.rc2.18.g61b472e

12 years, 2 months

Re: Optimizing Linux with cheap flash drives

by Arnd Bergmann

On Monday 31 December 2012, Phillip Norisez wrote: > Hello. > > Are you the Arnd Bergmann that published the article "Optimizing Linux > with cheap flash drives" in lwm.net on February 18, 2011? If so, I > would greatly appreciate it if you could answer a question. Yes, that is me. > My name is Phillip Norisez and I am in the process of putting together > an embedded Linux on a custom-designed board using a TI ARM DM3055 > microprocessor. My question is, is there any updated information > about using SD cards as Linux boot devices, especially as regards both > the incompatibilities your article raises and lifetime expectations? > > This latter is due to the fact that the board will be used as part of a > device which must be usable indefinitely in a third-world environment, > without access to high-tech facilities, but must last longer than the > typical cell phone. There are two important recommendations I have: * The Samsung 32GB Class 10 MB-SSBGA and MB-MSBGA cards are apparently based on an eMMC controller that has much better characteristics when using a nonstandard file system on them. This does not apply to the smaller cards or to any other brands I have seen, and of course it may change in the future. I have not yet tested Samsungs new UHS-1 compatible version of those cards. * The new f2fs file system has been merged into the linux kernel for version 3.8. This should have a *much* better long term reliability for normal cards than any of the existing file systems we have in Linux. It is fairly new, so I would not consider it as stable as the other file systems, but on unreliable SD cards, the end result is probably better, especially if the product you want to ship is going to upgrade to a future kernel version that fixes the bugs that are yet to be found. > You may reply to this e-mail directly if so inclined. If you would > prefer that I post this on a message board, please reply with its URL. For more questions, please use the linaro-dev(a)lists.linaro.org mailing list but keep me on Cc. Arnd

12 years, 2 months

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linaro-dev January 2013