| Message ID | 1394732168-12638-2-git-send-email-dirk.j.brandewie@intel.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
On 03/13/2014 11:06 PM, dirk.brandewie@gmail.com wrote: > From: Dirk Brandewie <dirk.j.brandewie@intel.com> > > This callback allows the driver to do clean up before the CPU is > completely down and its state cannot be modified. This is used > by the intel_pstate driver to reduce the requested P state prior to > the core going away. This is required because the requested P state > of the offline core is used to select the package P state. This > effectively sets the floor package P state to the requested P state on > the offline core. > > Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com> > --- > Documentation/cpu-freq/cpu-drivers.txt | 8 +++++++- > drivers/cpufreq/cpufreq.c | 3 +++ > include/linux/cpufreq.h | 1 + > 3 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt > index 8b1a445..935f274 100644 > --- a/Documentation/cpu-freq/cpu-drivers.txt > +++ b/Documentation/cpu-freq/cpu-drivers.txt > @@ -61,7 +61,13 @@ target_index - See below on the differences. > > And optionally > > -cpufreq_driver.exit - A pointer to a per-CPU cleanup function. > +cpufreq_driver.exit - A pointer to a per-CPU cleanup > + function called during CPU_POST_DEAD > + phase of cpu hotplug process. > + > +cpufreq_driver.exit_prepare - A pointer to a per-CPU cleanup function > + called during CPU_DOWN_PREPARE phase of > + cpu hotplug process. > > cpufreq_driver.resume - A pointer to a per-CPU resume function > which is called with interrupts disabled > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index cf485d9..5c9bbfa 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -1338,6 +1338,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev, > } > } > > + if (cpufreq_driver->exit_prepare) > + cpufreq_driver->exit_prepare(policy); > + The placement of this hunk doesn't feel right. IMHO we should place it right next to the code which stops the governor. Something like this: if (has_target()) { ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP); if (ret) { pr_err("%s: Failed to stop governor\n", __func__); return ret; } } else if (cpufreq_driver->setpolicy) { if (cpufreq_driver->exit_prepare) cpufreq_driver->exit_prepare(policy); } This makes it clear that GOV_STOP is used to stop managing the CPUs for platforms that have ->target defined, and ->exit_prepare() is used for similar purposes for platforms that have ->setpolicy() defined. By the way, I like the name ->stop more than ->exit_prepare, because: ->exit() is done once per policy, which implies that ->exit_prepare also shares similar semantics. However, what we really want the new callback to do is to provide a way for the driver to stop managing the CPU that is going offline, just like GOV_STOP. So naturally, this new callback should be invoked during every CPU offline, and not just once per policy. Hence the name "stop" (this CPU) makes perfect sense for that IMHO. [Of course, I understand that GOV_STOP actually stops the entire policy for all affected cpus and then we use GOV_START in _remove_dev_finish() to restart the governor for the other online CPUs in that policy. This is somewhat round-about, but conceptually this is equivalent to asking the governor to let go control of only the CPU going offline. The new ->stop callback should have the same "stop only this CPU" semantics.] > return 0; > } > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index 4d89e0e..5fa94ad 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -224,6 +224,7 @@ struct cpufreq_driver { > int (*bios_limit) (int cpu, unsigned int *limit); > > int (*exit) (struct cpufreq_policy *policy); > + int (*exit_prepare) (struct cpufreq_policy *policy); > int (*suspend) (struct cpufreq_policy *policy); > int (*resume) (struct cpufreq_policy *policy); > struct freq_attr **attr; > -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt index 8b1a445..935f274 100644 --- a/Documentation/cpu-freq/cpu-drivers.txt +++ b/Documentation/cpu-freq/cpu-drivers.txt @@ -61,7 +61,13 @@ target_index - See below on the differences. And optionally -cpufreq_driver.exit - A pointer to a per-CPU cleanup function. +cpufreq_driver.exit - A pointer to a per-CPU cleanup + function called during CPU_POST_DEAD + phase of cpu hotplug process. + +cpufreq_driver.exit_prepare - A pointer to a per-CPU cleanup function + called during CPU_DOWN_PREPARE phase of + cpu hotplug process. cpufreq_driver.resume - A pointer to a per-CPU resume function which is called with interrupts disabled diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index cf485d9..5c9bbfa 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1338,6 +1338,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev, } } + if (cpufreq_driver->exit_prepare) + cpufreq_driver->exit_prepare(policy); + return 0; } diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 4d89e0e..5fa94ad 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -224,6 +224,7 @@ struct cpufreq_driver { int (*bios_limit) (int cpu, unsigned int *limit); int (*exit) (struct cpufreq_policy *policy); + int (*exit_prepare) (struct cpufreq_policy *policy); int (*suspend) (struct cpufreq_policy *policy); int (*resume) (struct cpufreq_policy *policy); struct freq_attr **attr;