* [PATCH 0/2] cpufreq: Allow light-weight tear down on CPU offline @ 2019-02-11 8:41 Viresh Kumar 2019-02-11 8:41 ` [PATCH 1/2] cpufreq: Allow light-weight tear down on CPU offline operation Viresh Kumar 2019-02-11 8:41 ` [PATCH 2/2] cpufreq: dt: Implement light_weight_exit() callback Viresh Kumar 0 siblings, 2 replies; 5+ messages in thread From: Viresh Kumar @ 2019-02-11 8:41 UTC (permalink / raw) To: Rafael Wysocki Cc: Viresh Kumar, linux-pm, Vincent Guittot, Sudeep Holla, Marek Szyprowski, linux-kernel The cpufreq core doesn't remove the cpufreq policy anymore on CPU offline operation, rather that happens when the CPU device gets unregistered from the kernel. This allows faster recovery when the CPU comes back online. This is also very useful during system wide suspend/resume where we offline all non-boot CPUs during suspend and then bring them back on resume. This patcset takes the same idea a step ahead to allow drivers to do light weight tear-down during CPU offline operation and updates the cpufreq-dt driver to implement the new helper. Viresh Kumar (2): cpufreq: Allow light-weight tear down on CPU offline operation cpufreq: dt: Implement light_weight_exit() callback drivers/cpufreq/cpufreq-dt.c | 19 +++++++++++++++++++ drivers/cpufreq/cpufreq.c | 16 +++++++++++----- include/linux/cpufreq.h | 1 + 3 files changed, 31 insertions(+), 5 deletions(-) -- 2.20.1.321.g9e740568ce00 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 1/2] cpufreq: Allow light-weight tear down on CPU offline operation 2019-02-11 8:41 [PATCH 0/2] cpufreq: Allow light-weight tear down on CPU offline Viresh Kumar @ 2019-02-11 8:41 ` Viresh Kumar 2019-02-11 10:51 ` Rafael J. Wysocki 2019-02-11 8:41 ` [PATCH 2/2] cpufreq: dt: Implement light_weight_exit() callback Viresh Kumar 1 sibling, 1 reply; 5+ messages in thread From: Viresh Kumar @ 2019-02-11 8:41 UTC (permalink / raw) To: Rafael Wysocki Cc: Viresh Kumar, linux-pm, Vincent Guittot, Sudeep Holla, Marek Szyprowski, linux-kernel The cpufreq core doesn't remove the cpufreq policy anymore on CPU offline operation, rather that happens when the CPU device gets unregistered from the kernel. This allows faster recovery when the CPU comes back online. This is also very useful during system wide suspend/resume where we offline all non-boot CPUs during suspend and then bring them back on resume. This commit takes the same idea a step ahead to allow drivers to do light weight tear-down during CPU offline operation. A new callback is introduced, light_weight_exit(), which gets called when all the CPUs of a policy are removed/offlined and the existing exit() callback gets called when the policy gets freed. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/cpufreq.c | 16 +++++++++++----- include/linux/cpufreq.h | 1 + 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 96a69c67a545..215a8bfc78bb 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1421,11 +1421,12 @@ static int cpufreq_offline(unsigned int cpu) cpufreq_exit_governor(policy); /* - * Perform the ->exit() even during light-weight tear-down, - * since this is a core component, and is essential for the - * subsequent light-weight ->init() to succeed. + * Perform the ->light_weight_exit() during light-weight tear-down, as + * that allows fast recovery when the CPU comes back. */ - if (cpufreq_driver->exit) { + if (cpufreq_driver->light_weight_exit) { + cpufreq_driver->light_weight_exit(policy); + } else if (cpufreq_driver->exit) { cpufreq_driver->exit(policy); policy->freq_table = NULL; } @@ -1454,8 +1455,13 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) cpumask_clear_cpu(cpu, policy->real_cpus); remove_cpu_dev_symlink(policy, dev); - if (cpumask_empty(policy->real_cpus)) + if (cpumask_empty(policy->real_cpus)) { + /* We did light-weight exit earlier, do full tear down now */ + if (cpufreq_driver->light_weight_exit) + cpufreq_driver->exit(policy); + cpufreq_policy_free(policy); + } } /** diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 9db074ecbbd7..36ce31516041 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -325,6 +325,7 @@ struct cpufreq_driver { /* optional */ int (*bios_limit)(int cpu, unsigned int *limit); + int (*light_weight_exit)(struct cpufreq_policy *policy); int (*exit)(struct cpufreq_policy *policy); void (*stop_cpu)(struct cpufreq_policy *policy); int (*suspend)(struct cpufreq_policy *policy); -- 2.20.1.321.g9e740568ce00 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] cpufreq: Allow light-weight tear down on CPU offline operation 2019-02-11 8:41 ` [PATCH 1/2] cpufreq: Allow light-weight tear down on CPU offline operation Viresh Kumar @ 2019-02-11 10:51 ` Rafael J. Wysocki 2019-02-11 10:56 ` Rafael J. Wysocki 0 siblings, 1 reply; 5+ messages in thread From: Rafael J. Wysocki @ 2019-02-11 10:51 UTC (permalink / raw) To: Viresh Kumar Cc: Rafael Wysocki, Linux PM, Vincent Guittot, Sudeep Holla, Marek Szyprowski, Linux Kernel Mailing List On Mon, Feb 11, 2019 at 9:41 AM Viresh Kumar <viresh.kumar@linaro.org> wrote: > > The cpufreq core doesn't remove the cpufreq policy anymore on CPU > offline operation, rather that happens when the CPU device gets > unregistered from the kernel. This allows faster recovery when the CPU > comes back online. This is also very useful during system wide > suspend/resume where we offline all non-boot CPUs during suspend and > then bring them back on resume. > > This commit takes the same idea a step ahead to allow drivers to do > light weight tear-down during CPU offline operation. > > A new callback is introduced, light_weight_exit(), which gets called > when all the CPUs of a policy are removed/offlined and the existing > exit() callback gets called when the policy gets freed. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq.c | 16 +++++++++++----- > include/linux/cpufreq.h | 1 + > 2 files changed, 12 insertions(+), 5 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 96a69c67a545..215a8bfc78bb 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -1421,11 +1421,12 @@ static int cpufreq_offline(unsigned int cpu) > cpufreq_exit_governor(policy); > > /* > - * Perform the ->exit() even during light-weight tear-down, > - * since this is a core component, and is essential for the > - * subsequent light-weight ->init() to succeed. > + * Perform the ->light_weight_exit() during light-weight tear-down, as > + * that allows fast recovery when the CPU comes back. > */ > - if (cpufreq_driver->exit) { > + if (cpufreq_driver->light_weight_exit) { > + cpufreq_driver->light_weight_exit(policy); > + } else if (cpufreq_driver->exit) { > cpufreq_driver->exit(policy); > policy->freq_table = NULL; > } > @@ -1454,8 +1455,13 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) > cpumask_clear_cpu(cpu, policy->real_cpus); > remove_cpu_dev_symlink(policy, dev); > > - if (cpumask_empty(policy->real_cpus)) > + if (cpumask_empty(policy->real_cpus)) { > + /* We did light-weight exit earlier, do full tear down now */ > + if (cpufreq_driver->light_weight_exit) > + cpufreq_driver->exit(policy); > + > cpufreq_policy_free(policy); > + } > } > > /** > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index 9db074ecbbd7..36ce31516041 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -325,6 +325,7 @@ struct cpufreq_driver { > /* optional */ > int (*bios_limit)(int cpu, unsigned int *limit); > > + int (*light_weight_exit)(struct cpufreq_policy *policy); Can you call it "offline"? > int (*exit)(struct cpufreq_policy *policy); > void (*stop_cpu)(struct cpufreq_policy *policy); > int (*suspend)(struct cpufreq_policy *policy); > -- ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] cpufreq: Allow light-weight tear down on CPU offline operation 2019-02-11 10:51 ` Rafael J. Wysocki @ 2019-02-11 10:56 ` Rafael J. Wysocki 0 siblings, 0 replies; 5+ messages in thread From: Rafael J. Wysocki @ 2019-02-11 10:56 UTC (permalink / raw) To: Viresh Kumar Cc: Rafael Wysocki, Linux PM, Vincent Guittot, Sudeep Holla, Marek Szyprowski, Linux Kernel Mailing List On Mon, Feb 11, 2019 at 11:51 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Mon, Feb 11, 2019 at 9:41 AM Viresh Kumar <viresh.kumar@linaro.org> wrote: > > > > The cpufreq core doesn't remove the cpufreq policy anymore on CPU > > offline operation, rather that happens when the CPU device gets > > unregistered from the kernel. This allows faster recovery when the CPU > > comes back online. This is also very useful during system wide > > suspend/resume where we offline all non-boot CPUs during suspend and > > then bring them back on resume. > > > > This commit takes the same idea a step ahead to allow drivers to do > > light weight tear-down during CPU offline operation. > > > > A new callback is introduced, light_weight_exit(), which gets called > > when all the CPUs of a policy are removed/offlined and the existing > > exit() callback gets called when the policy gets freed. > > > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > > --- [cut] > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > > index 9db074ecbbd7..36ce31516041 100644 > > --- a/include/linux/cpufreq.h > > +++ b/include/linux/cpufreq.h > > @@ -325,6 +325,7 @@ struct cpufreq_driver { > > /* optional */ > > int (*bios_limit)(int cpu, unsigned int *limit); > > > > + int (*light_weight_exit)(struct cpufreq_policy *policy); > > Can you call it "offline"? > > > int (*exit)(struct cpufreq_policy *policy); > > void (*stop_cpu)(struct cpufreq_policy *policy); > > int (*suspend)(struct cpufreq_policy *policy); > > -- Also, I would prefer a corresponding "online" callback to be there too for symmetry and I'd prefer the core to decide to call "online" instead of "init" for the light-weight case instead of ->init() itself having to figure out the context. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 2/2] cpufreq: dt: Implement light_weight_exit() callback 2019-02-11 8:41 [PATCH 0/2] cpufreq: Allow light-weight tear down on CPU offline Viresh Kumar 2019-02-11 8:41 ` [PATCH 1/2] cpufreq: Allow light-weight tear down on CPU offline operation Viresh Kumar @ 2019-02-11 8:41 ` Viresh Kumar 1 sibling, 0 replies; 5+ messages in thread From: Viresh Kumar @ 2019-02-11 8:41 UTC (permalink / raw) To: Rafael Wysocki Cc: Viresh Kumar, linux-pm, Vincent Guittot, Sudeep Holla, Marek Szyprowski, linux-kernel Implement the light-weight tear down helper to reduce the amount of work to do on CPU offline/online operation. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/cpufreq-dt.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c index 7ba392911cd0..69309a8121f0 100644 --- a/drivers/cpufreq/cpufreq-dt.c +++ b/drivers/cpufreq/cpufreq-dt.c @@ -160,6 +160,15 @@ static int cpufreq_init(struct cpufreq_policy *policy) const char *name; int ret; + /* + * We did light-weight shutdown earlier, nothing else to initialize here + * apart from policy->cpus. + */ + if (policy->driver_data) { + cpumask_copy(policy->cpus, policy->related_cpus); + return 0; + } + cpu_dev = get_cpu_device(policy->cpu); if (!cpu_dev) { pr_err("failed to get cpu%d device\n", policy->cpu); @@ -295,6 +304,15 @@ static int cpufreq_init(struct cpufreq_policy *policy) return ret; } +static int cpufreq_light_weight_exit(struct cpufreq_policy *policy) +{ + /* + * Preserve policy->driver_data and don't free resources on light-weight + * tear down. + */ + return 0; +} + static int cpufreq_exit(struct cpufreq_policy *policy) { struct private_data *priv = policy->driver_data; @@ -319,6 +337,7 @@ static struct cpufreq_driver dt_cpufreq_driver = { .get = cpufreq_generic_get, .init = cpufreq_init, .exit = cpufreq_exit, + .light_weight_exit = cpufreq_light_weight_exit, .name = "cpufreq-dt", .attr = cpufreq_dt_attr, .suspend = cpufreq_generic_suspend, -- 2.20.1.321.g9e740568ce00 ^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-02-11 10:56 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-02-11 8:41 [PATCH 0/2] cpufreq: Allow light-weight tear down on CPU offline Viresh Kumar 2019-02-11 8:41 ` [PATCH 1/2] cpufreq: Allow light-weight tear down on CPU offline operation Viresh Kumar 2019-02-11 10:51 ` Rafael J. Wysocki 2019-02-11 10:56 ` Rafael J. Wysocki 2019-02-11 8:41 ` [PATCH 2/2] cpufreq: dt: Implement light_weight_exit() callback Viresh Kumar
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