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path: root/drivers/cpufreq/cpufreq_ondemand.c
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2017-07-22cpufreq: governor: Drop min_sampling_rateViresh Kumar
The cpufreq core and governors aren't supposed to set a limit on how fast we want to try changing the frequency. This is currently done for the legacy governors with help of min_sampling_rate. At worst, we may end up setting the sampling rate to a value lower than the rate at which frequency can be changed and then one of the CPUs in the policy will be only changing frequency for ever. But that is something for the user to decide and there is no need to have special handling for such cases in the core. Leave it for the user to figure out. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/cpufreq.h> We are going to split <linux/sched/cpufreq.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/cpufreq.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-12-01cpufreq: ondemand: Set MIN_FREQUENCY_UP_THRESHOLD to 1Chen Yu
Currently the minimal up_threshold is 11, and user may want to use a smaller minimal up_threshold for performance tuning, so MIN_FREQUENCY_UP_THRESHOLD could be set to 1 because: 1. Current systems wouldn't be affected as they have already a value >= 11. 2. New systems with a default kernel would keep still the default value that is >= 11. Users now have the advantage that they can make their own decisions and customize the 'trip point' to switch to the max frequency. Link: https://bugzilla.kernel.org/show_bug.cgi?id=65501 Signed-off-by: Chen Yu <yu.c.chen@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-11cpufreq: governor: Don't use 'timer' keywordViresh Kumar
The earlier implementation of governors used background timers and so functions, mutex, etc had 'timer' keyword in their names. But that's not true anymore. Replace 'timer' with 'update', as those functions, variables are based around updates to frequency. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-07cpufreq: Reuse new freq-table helpersViresh Kumar
This patch migrates few users of cpufreq tables to the new helpers that work on sorted freq-tables. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-09cpufreq: Return index from cpufreq_frequency_table_target()Viresh Kumar
This routine can't fail unless the frequency table is invalid and doesn't contain any valid entries. Make it return the index and WARN() in case it is used for an invalid table. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-09cpufreq: Drop freq-table param to cpufreq_frequency_table_target()Viresh Kumar
The policy already has this pointer set, use it instead. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-09cpufreq: ondemand: Don't keep a copy of freq_table pointerViresh Kumar
There is absolutely no need to keep a copy to the freq-table in 'struct od_policy_dbs_info'. Use policy->freq_table instead. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-09cpufreq: Remove cpufreq_frequency_get_table()Viresh Kumar
Most of the callers of cpufreq_frequency_get_table() already have the pointer to a valid 'policy' structure and they don't really need to go through the per-cpu variable first and then a check to validate the frequency, in order to find the freq-table for the policy. Directly use the policy->freq_table field instead for them. Only one user of that API is left after above changes, cpu_cooling.c and it accesses the freq_table in a racy way as the policy can get freed in between. Fix it by using cpufreq_cpu_get() properly. Since there are no more users of cpufreq_frequency_get_table() left, get rid of it. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Javi Merino <javi.merino@arm.com> (cpu_cooling.c) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-02cpufreq: Drop the 'initialized' field from struct cpufreq_governorRafael J. Wysocki
The 'initialized' field in struct cpufreq_governor is only used by the conservative governor (as a usage counter) and the way that happens is far from straightforward and arguably incorrect. Namely, the value of 'initialized' is checked by cpufreq_dbs_governor_init() and cpufreq_dbs_governor_exit() and the results of those checks are passed (as the second argument) to the ->init() and ->exit() callbacks in struct dbs_governor. Those callbacks are only implemented by the ondemand and conservative governors and ondemand doesn't use their second argument at all. In turn, the conservative governor uses it to decide whether or not to either register or unregister a transition notifier. That whole mechanism is not only unnecessarily convoluted, but also racy, because the 'initialized' field of struct cpufreq_governor is updated in cpufreq_init_governor() and cpufreq_exit_governor() under policy->rwsem which doesn't help if one of these functions is run twice in parallel for different policies (which isn't impossible in principle), for example. Instead of it, add a proper usage counter to the conservative governor and update it from cs_init() and cs_exit() which is guaranteed to be non-racy, as those functions are only called under gov_dbs_data_mutex which is global. With that in place, drop the 'initialized' field from struct cpufreq_governor as it is not used any more. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-06-02cpufreq: governor: Remove prints from allocation failuresViresh Kumar
These aren't required anymore as the allocation core already prints such messages. Remove the redundant ones. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-02cpufreq: governor: Get rid of governor eventsRafael J. Wysocki
The design of the cpufreq governor API is not very straightforward, as struct cpufreq_governor provides only one callback to be invoked from different code paths for different purposes. The purpose it is invoked for is determined by its second "event" argument, causing it to act as a "callback multiplexer" of sorts. Unfortunately, that leads to extra complexity in governors, some of which implement the ->governor() callback as a switch statement that simply checks the event argument and invokes a separate function to handle that specific event. That extra complexity can be eliminated by replacing the all-purpose ->governor() callback with a family of callbacks to carry out specific governor operations: initialization and exit, start and stop and policy limits updates. That also turns out to reduce the code size too, so do it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-04-02cpufreq: governor: New data type for management part of dbs_dataRafael J. Wysocki
In addition to fields representing governor tunables, struct dbs_data contains some fields needed for the management of objects of that type. As it turns out, that part of struct dbs_data may be shared with (future) governors that won't use the common code used by "ondemand" and "conservative", so move it to a separate struct type and modify the code using struct dbs_data to follow. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Move per-CPU data to the common codeRafael J. Wysocki
After previous changes there is only one piece of code in the ondemand governor making references to per-CPU data structures, but it can be easily modified to avoid doing that, so modify it accordingly and move the definition of per-CPU data used by the ondemand and conservative governors to the common code. Next, change that code to access the per-CPU data structures directly rather than via a governor callback. This causes the ->get_cpu_cdbs governor callback to become unnecessary, so drop it along with the macro and function definitions related to it. Finally, drop the definitions of struct od_cpu_dbs_info_s and struct cs_cpu_dbs_info_s that aren't necessary any more. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Make governor private data per-policyRafael J. Wysocki
Some fields in struct od_cpu_dbs_info_s and struct cs_cpu_dbs_info_s are only used for a limited set of CPUs. Namely, if a policy is shared between multiple CPUs, those fields will only be used for one of them (policy->cpu). This means that they really are per-policy rather than per-CPU and holding room for them in per-CPU data structures is generally wasteful. Also moving those fields into per-policy data structures will allow some significant simplifications to be made going forward. For this reason, introduce struct cs_policy_dbs_info and struct od_policy_dbs_info to hold those fields. Define each of the new structures as an extension of struct policy_dbs_info (such that struct policy_dbs_info is embedded in each of them) and introduce new ->alloc and ->free governor callbacks to allocate and free those structures, respectively, such that ->alloc() will return a pointer to the struct policy_dbs_info embedded in the allocated data structure and ->free() will take that pointer as its argument. With that, modify the code accessing the data fields in question in per-CPU data objects to look for them in the new structures via the struct policy_dbs_info pointer available to it and drop them from struct od_cpu_dbs_info_s and struct cs_cpu_dbs_info_s. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: ondemand: Rework the handling of powersave bias updatesRafael J. Wysocki
The ondemand_powersave_bias_init() function used for resetting data fields related to the powersave bias tunable of the ondemand governor works by walking all of the online CPUs in the system and updating the od_cpu_dbs_info_s structures for all of them. However, if governor tunables are per policy, the update should not touch the CPUs that are not associated with the given dbs_data. Moreover, since the data fields in question are only ever used for policy->cpu in each policy governed by ondemand, the update can be limited to those specific CPUs. Rework the code to take the above observations into account. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Fix CPU load information updates via ->storeRafael J. Wysocki
The ->store() callbacks of some tunable sysfs attributes of the ondemand and conservative governors trigger immediate updates of the CPU load information for all CPUs "governed" by the given dbs_data by walking the cpu_dbs_info structures for all online CPUs in the system and updating them. This is questionable for two reasons. First, it may lead to a lot of extra overhead on a system with many CPUs if the given dbs_data is only associated with a few of them. Second, if governor tunables are per-policy, the CPUs associated with the other sets of governor tunables should not be updated. To address this issue, use the observation that in all of the places in question the update operation may be carried out in the same way (because all of the tunables involved are now located in struct dbs_data and readily available to the common code) and make the code in those places invoke the same (new) helper function that will carry out the update correctly. That new function always checks the ignore_nice_load tunable value and updates the CPUs' prev_cpu_nice data fields if that's set, which wasn't done by the original code in store_io_is_busy(), but it should have been done in there too. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: ondemand: Drop one more callback from struct od_opsRafael J. Wysocki
The ->powersave_bias_init_cpu callback in struct od_ops is only used in one place and that invocation may be replaced with a direct call to the function pointed to by that callback, so change the code accordingly and drop the callback. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Drop unused governor callback and data fieldsRafael J. Wysocki
After some previous changes, the ->get_cpu_dbs_info_s governor callback and the "governor" field in struct dbs_governor (whose value represents the governor type) are not used any more, so drop them. Also drop the unused gov_ops field from struct dbs_governor. No functional changes. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Add a ->start callback for governorsRafael J. Wysocki
To avoid having to check the governor type explicitly in the common code in order to initialize data structures specific to the governor type properly, add a ->start callback to struct dbs_governor and use it to initialize those data structures for the ondemand and conservative governors. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Move io_is_busy to struct dbs_dataRafael J. Wysocki
The io_is_busy governor tunable is only used by the ondemand governor and is located in the ondemand-specific data structure, but it is looked at by the common governor code that has to do ugly things to get to that value, so move it to struct dbs_data and modify ondemand accordingly. Since the conservative governor never touches that field, it will be always 0 for that governor and it won't have any effect on the results of computations in that case. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: ondemand: Drop unused callback from struct od_opsRafael J. Wysocki
The ->freq_increase callback in struct od_ops is never invoked, so drop it. No functional changes. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: ondemand: Simplify od_update() slightlyRafael J. Wysocki
Drop some lines of code from od_update() by arranging the statements in there in a more logical way. No functional changes. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Use microseconds in sample delay computationsRafael J. Wysocki
Do not convert microseconds to jiffies and the other way around in governor computations related to the sampling rate and sample delay and drop delay_for_sampling_rate() which isn't of any use then. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: ondemand: Simplify conditionals in od_dbs_timer()Rafael J. Wysocki
Reduce the indentation level in the conditionals in od_dbs_timer() and drop the delay variable from it. No functional changes. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Move rate_mult to struct policy_dbsRafael J. Wysocki
The rate_mult field in struct od_cpu_dbs_info_s is used by the code shared with the conservative governor and to access it that code has to do an ugly governor type check. However, first of all it is ever only used for policy->cpu, so it is per-policy rather than per-CPU and second, it is initialized to 1 by cpufreq_governor_start(), so if the conservative governor never modifies it, it will have no effect on the results of any computations. For these reasons, move rate_mult to struct policy_dbs_info (as a common field). Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Get rid of the ->gov_check_cpu callbackRafael J. Wysocki
The way the ->gov_check_cpu governor callback is used by the ondemand and conservative governors is not really straightforward. Namely, the governor calls dbs_check_cpu() that updates the load information for the policy and the invokes ->gov_check_cpu() for the governor. To get rid of that entanglement, notice that cpufreq_governor_limits() doesn't need to call dbs_check_cpu() directly. Instead, it can simply reset the sample delay to 0 which will cause a sample to be taken immediately. The result of that is practically equivalent to calling dbs_check_cpu() except that it will trigger a full update of governor internal state and not just the ->gov_check_cpu() part. Following that observation, make cpufreq_governor_limits() reset the sample delay and turn dbs_check_cpu() into a function that will simply evaluate the load and return the result called dbs_update(). That function can now be called by governors from the routines that previously were pointed to by ->gov_check_cpu and those routines can be called directly by each governor instead of dbs_check_cpu(). This way ->gov_check_cpu becomes unnecessary, so drop it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: ondemand: Rearrange od_dbs_timer() to avoid updating delayViresh Kumar
Avoid extra checks in od_dbs_timer() by rearranging updates to the local delay variable in it. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> [ rjw: Changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-09cpufreq: conservative: Update sample_delay_ns immediatelyViresh Kumar
The ondemand governor already updates sample_delay_ns immediately on updates to the sampling rate, but conservative doesn't do that. It was left out earlier as the code was really too complex to get that done easily. Things are sorted out very well now, however, and the conservative governor can be modified to follow ondemand in that respect. Moreover, since the code needed to implement that in the conservative governor would be identical to the corresponding ondemand governor's code, make that code common and change both governors to use it. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Juri Lelli <juri.lelli@arm.com> Tested-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> [ rjw: Changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-09cpufreq: governor: Create and traverse list of policy_dbs to avoid deadlockViresh Kumar
The dbs_data_mutex lock is currently used in two places. First, cpufreq_governor_dbs() uses it to guarantee mutual exclusion between invocations of governor operations from the core. Second, it is used by ondemand governor's update_sampling_rate() to ensure the stability of data structures walked by it. The second usage is quite problematic, because update_sampling_rate() is called from a governor sysfs attribute's ->store callback and that leads to a deadlock scenario involving cpufreq_governor_exit() which runs under dbs_data_mutex. Thus it is better to rework the code so update_sampling_rate() doesn't need to acquire dbs_data_mutex. To that end, rework update_sampling_rate() to walk a list of policy_dbs objects supported by the dbs_data one it has been called for (instead of walking cpu_dbs_info object for all CPUs). The list manipulation is protected with dbs_data->mutex which also is held around the execution of update_sampling_rate(), it is not necessary to hold dbs_data_mutex in that function any more. Reported-by: Juri Lelli <juri.lelli@arm.com> Reported-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> [ rjw: Subject & changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-09cpufreq: governor: New sysfs show/store callbacks for governor tunablesViresh Kumar
The ondemand and conservative governors use the global-attr or freq-attr structures to represent sysfs attributes corresponding to their tunables (which of them is actually used depends on whether or not different policy objects can use the same governor with different tunables at the same time and, consequently, on where those attributes are located in sysfs). Unfortunately, in the freq-attr case, the standard cpufreq show/store sysfs attribute callbacks are applied to the governor tunable attributes and they always acquire the policy->rwsem lock before carrying out the operation. That may lead to an ABBA deadlock if governor tunable attributes are removed under policy->rwsem while one of them is being accessed concurrently (if sysfs attributes removal wins the race, it will wait for the access to complete with policy->rwsem held while the attribute callback will block on policy->rwsem indefinitely). We attempted to address this issue by dropping policy->rwsem around governor tunable attributes removal (that is, around invocations of the ->governor callback with the event arg equal to CPUFREQ_GOV_POLICY_EXIT) in cpufreq_set_policy(), but that opened up race conditions that had not been possible with policy->rwsem held all the time. Therefore policy->rwsem cannot be dropped in cpufreq_set_policy() at any point, but the deadlock situation described above must be avoided too. To that end, use the observation that in principle governor tunables may be represented by the same data type regardless of whether the governor is system-wide or per-policy and introduce a new structure, struct governor_attr, for representing them and new corresponding macros for creating show/store sysfs callbacks for them. Also make their parent kobject use a new kobject type whose default show/store callbacks are not related to the standard core cpufreq ones in any way (and they don't acquire policy->rwsem in particular). Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Juri Lelli <juri.lelli@arm.com> Tested-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> [ rjw: Subject & changelog + rebase ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-09cpufreq: governor: Move common tunables to 'struct dbs_data'Viresh Kumar
There are a few common tunables shared between the ondemand and conservative governors. Move them to struct dbs_data to simplify code. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Juri Lelli <juri.lelli@arm.com> Tested-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> [ rjw: Changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-09cpufreq: governor: Create generic macro for common tunablesViresh Kumar
Some tunables are present in governor-specific structures, whereas one (min_sampling_rate) is located directly in struct dbs_data. There is a special macro for creating its sysfs attribute and the show/store callbacks, but since more tunables are going to be moved to struct dbs_data, a new generic macro for such cases will be useful, so add it and use it for min_sampling_rate. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Juri Lelli <juri.lelli@arm.com> Tested-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> [ rjw: Subject & changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-03-09cpufreq: governor: Rearrange governor data structuresRafael J. Wysocki
The struct policy_dbs_info objects representing per-policy governor data are not accessible directly from the corresponding policy objects. To access them, one has to get a pointer to the struct cpu_dbs_info of policy->cpu and use the policy_dbs field of that which isn't really straightforward. To address that rearrange the governor data structures so the governor_data pointer in struct cpufreq_policy will point to struct policy_dbs_info (instead of struct dbs_data) and that will contain a pointer to struct dbs_data. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Drop cpu argument from dbs_check_cpu()Rafael J. Wysocki
Since policy->cpu is always passed as the second argument to dbs_check_cpu(), it is not really necessary to pass it, because the function can obtain that value via its first argument just fine. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Rename cpu_common_dbs_info to policy_dbs_infoRafael J. Wysocki
The struct cpu_common_dbs_info structure represents the per-policy part of the governor data (for the ondemand and conservative governors), but its name doesn't reflect its purpose. Rename it to struct policy_dbs_info and rename variables related to it accordingly. No functional changes. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Drop the gov pointer from struct dbs_dataRafael J. Wysocki
Since it is possible to obtain a pointer to struct dbs_governor from a pointer to the struct governor embedded in it with the help of container_of(), the additional gov pointer in struct dbs_data isn't really necessary. Drop that pointer and make the code using it reach the dbs_governor object via policy->governor. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Rework cpufreq_governor_dbs()Rafael J. Wysocki
Since it is possible to obtain a pointer to struct dbs_governor from a pointer to the struct governor embedded in it via container_of(), the second argument of cpufreq_governor_init() is not necessary. Accordingly, cpufreq_governor_dbs() doesn't need its second argument either and the ->governor callbacks for both the ondemand and conservative governors may be set to cpufreq_governor_dbs() directly. Make that happen. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Rename some data types and variablesRafael J. Wysocki
The ondemand and conservative governors are represented by struct common_dbs_data whose name doesn't reflect the purpose it is used for, so rename it to struct dbs_governor and rename variables of that type accordingly. No functional changes. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Put governor structure into common_dbs_dataRafael J. Wysocki
For the ondemand and conservative governors (generally, governors that use the common code in cpufreq_governor.c), there are two static data structures representing the governor, the struct governor structure (the interface to the cpufreq core) and the struct common_dbs_data one (the interface to the cpufreq_governor.c code). There's no fundamental reason why those two structures have to be separate. Moreover, if the struct governor one is included into struct common_dbs_data, it will be possible to reach the latter from the policy via its policy->governor pointer, so it won't be necessary to pass a separate pointer to it around. For this reason, embed struct governor in struct common_dbs_data. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Use common mutex for dbs_data protectionRafael J. Wysocki
Every governor relying on the common code in cpufreq_governor.c has to provide its own mutex in struct common_dbs_data. However, there actually is no need to have a separate mutex per governor for this purpose, they may be using the same global mutex just fine. Accordingly, introduce a single common mutex for that and drop the mutex field from struct common_dbs_data. That at least will ensure that the mutex is always present and initialized regardless of what the particular governors do. Another benefit is that the common code does not need a pointer to a governor-related structure to get to the mutex which sometimes helps. Finally, it makes the code generally easier to follow. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-03-09cpufreq: governor: Replace timers with utilization update callbacksRafael J. Wysocki
Instead of using a per-CPU deferrable timer for queuing up governor work items, register a utilization update callback that will be invoked from the scheduler on utilization changes. The sampling rate is still the same as what was used for the deferrable timers and the added irq_work overhead should be offset by the eliminated timers overhead, so in theory the functional impact of this patch should not be significant. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
2016-02-05cpufreq: Clean up default and fallback governor setupRafael J. Wysocki
The preprocessor magic used for setting the default cpufreq governor (and for using the performance governor as a fallback one for that matter) is really nasty, so replace it with __weak functions and overrides. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-12-09cpufreq: ondemand: update update_sampling_rate() to make it more efficientViresh Kumar
Currently update_sampling_rate() runs over each online CPU and cancels/queues timers on all policy->cpus every time. This should be done just once for any cpu belonging to a policy. Create a cpumask and keep on clearing it as and when we process policies, so that we don't have to traverse through all CPUs of the same policy. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-09cpufreq: governor: replace per-CPU delayed work with timersViresh Kumar
cpufreq governors evaluate load at sampling rate and based on that they update frequency for a group of CPUs belonging to the same cpufreq policy. This is required to be done in a single thread for all policy->cpus, but because we don't want to wakeup idle CPUs to do just that, we use deferrable work for this. If we would have used a single delayed deferrable work for the entire policy, there were chances that the CPU required to run the handler can be in idle and we might end up not changing the frequency for the entire group with load variations. And so we were forced to keep per-cpu works, and only the one that expires first need to do the real work and others are rescheduled for next sampling time. We have been using the more complex solution until now, where we used a delayed deferrable work for this, which is a combination of a timer and a work. This could be made lightweight by keeping per-cpu deferred timers with a single work item, which is scheduled by the first timer that expires. This patch does just that and here are important changes: - The timer handler will run in irq context and so we need to use a spin_lock instead of the timer_mutex. And so a separate timer_lock is created. This also makes the use of the mutex and lock quite clear, as we know what exactly they are protecting. - A new field 'skip_work' is added to track when the timer handlers can queue a work. More comments present in code. Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-07cpufreq: governor: Pass policy as argument to ->gov_dbs_timer()Viresh Kumar
Pass 'policy' as argument to ->gov_dbs_timer() instead of cdbs and dbs_data. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-07cpufreq: ondemand: Work is guaranteed to be pendingViresh Kumar
We are guaranteed to have works scheduled for policy->cpus, as the policy isn't stopped yet. And so there is no need to check that again. Drop it. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-07cpufreq: ondemand: Update sampling rate only for concerned policiesViresh Kumar
We are comparing policy->governor against cpufreq_gov_ondemand to make sure that we update sampling rate only for the concerned CPUs. But that isn't enough. In case of governor_per_policy, there can be multiple instances of ondemand governor and we will always end up updating all of them with current code. What we rather need to do, is to compare dbs_data with poilcy->governor_data, which will match only for the policies governed by dbs_data. This code is also racy as the governor might be getting stopped at that time and we may end up scheduling work for a policy, which we have just disabled. Fix that by protecting the entire function with &od_dbs_cdata.mutex, which will prevent against races with policy START/STOP/etc. After these locks are in place, we can safely get the policy via per-cpu dbs_info. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-10-28cpufreq: ondemand: Drop unnecessary locks from update_sampling_rate()Viresh Kumar
'timer_mutex' is required to sync work-handlers of policy->cpus. update_sampling_rate() is just canceling the works and queuing them again. This isn't protecting anything at all in update_sampling_rate() and is not gonna be of any use. Even if a work-handler is already running for a CPU, cancel_delayed_work_sync() will wait for it to finish. Drop these unnecessary locks. Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-07-21cpufreq: governor: split out common part of {cs|od}_dbs_timer()Viresh Kumar
Some part of cs_dbs_timer() and od_dbs_timer() is exactly same and is unnecessarily duplicated. Create the real work-handler in cpufreq_governor.c and put the common code in this routine (dbs_timer()). Shouldn't make any functional change. Reviewed-and-tested-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>