| Message ID | 1409234816-10802-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 28 August 2014 19:36, Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> wrote: > This patch ensures the cpus to kexec/reboot at nominal frequency. > Nominal frequency is the highest cpu frequency on PowerPC at > which the cores can run without getting throttled. > > If the host kernel had set the cpus to a low pstate and then it > kexecs/reboots to a cpufreq disabled kernel it would cause the target > kernel to perform poorly. It will also increase the boot up time of > the target kernel. So set the cpus to high pstate, in this case to > nominal frequency before rebooting to avoid such scenarios. > > The reboot notifier will set the cpus to nominal frequncy. > > Changes v1->v2: > Invoke .target() driver callback to set the cpus to nominal frequency > in reboot notifier, instead of calling cpufreq_suspend() as suggested > by Viresh Kumar. > Modified the commit message. This changelog will get commited, is this what you want? > Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> > Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> > --- > drivers/cpufreq/powernv-cpufreq.c | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c > index 379c083..ba27c49 100644 > --- a/drivers/cpufreq/powernv-cpufreq.c > +++ b/drivers/cpufreq/powernv-cpufreq.c > @@ -26,6 +26,7 @@ > #include <linux/cpufreq.h> > #include <linux/smp.h> > #include <linux/of.h> > +#include <linux/reboot.h> > > #include <asm/cputhreads.h> > #include <asm/firmware.h> > @@ -35,6 +36,7 @@ > #define POWERNV_MAX_PSTATES 256 > > static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; > +static bool rebooting; > > /* > * Note: The set of pstates consists of contiguous integers, the > @@ -284,6 +286,15 @@ static void set_pstate(void *freq_data) > } > > /* > + * get_nominal_index: Returns the index corresponding to the nominal > + * pstate in the cpufreq table > + */ > +static inline unsigned int get_nominal_index(void) > +{ > + return powernv_pstate_info.max - powernv_pstate_info.nominal; > +} > + > +/* > * powernv_cpufreq_target_index: Sets the frequency corresponding to > * the cpufreq table entry indexed by new_index on the cpus in the > * mask policy->cpus > @@ -293,6 +304,9 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy, > { > struct powernv_smp_call_data freq_data; > > + if (unlikely(rebooting) && new_index != get_nominal_index()) > + return -EBUSY; Have you placed the unlikely only around 'rebooting' intentionally or should it cover whole if statement? > + > freq_data.pstate_id = powernv_freqs[new_index].driver_data; > > /* > @@ -317,6 +331,25 @@ static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy) > return cpufreq_table_validate_and_show(policy, powernv_freqs); > } > > +static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb, > + unsigned long action, void *unused) > +{ > + int cpu; > + struct cpufreq_policy cpu_policy; > + > + rebooting = true; > + for_each_online_cpu(cpu) { > + cpufreq_get_policy(&cpu_policy, cpu); > + powernv_cpufreq_target_index(&cpu_policy, get_nominal_index()); > + } > + > + return NOTIFY_DONE; > +} > + > +static struct notifier_block powernv_cpufreq_reboot_nb = { > + .notifier_call = powernv_cpufreq_reboot_notifier, > +}; > + > static struct cpufreq_driver powernv_cpufreq_driver = { > .name = "powernv-cpufreq", > .flags = CPUFREQ_CONST_LOOPS, > @@ -342,12 +375,14 @@ static int __init powernv_cpufreq_init(void) > return rc; > } > > + register_reboot_notifier(&powernv_cpufreq_reboot_nb); > return cpufreq_register_driver(&powernv_cpufreq_driver); > } > module_init(powernv_cpufreq_init); > > static void __exit powernv_cpufreq_exit(void) > { > + unregister_reboot_notifier(&powernv_cpufreq_reboot_nb); > cpufreq_unregister_driver(&powernv_cpufreq_driver); > } > module_exit(powernv_cpufreq_exit); Looks fine otherwise. Acked-by: Viresh Kumar <viresh.kumar@linaro.org> -- 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/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index 379c083..ba27c49 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -26,6 +26,7 @@ #include <linux/cpufreq.h> #include <linux/smp.h> #include <linux/of.h> +#include <linux/reboot.h> #include <asm/cputhreads.h> #include <asm/firmware.h> @@ -35,6 +36,7 @@ #define POWERNV_MAX_PSTATES 256 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; +static bool rebooting; /* * Note: The set of pstates consists of contiguous integers, the @@ -284,6 +286,15 @@ static void set_pstate(void *freq_data) } /* + * get_nominal_index: Returns the index corresponding to the nominal + * pstate in the cpufreq table + */ +static inline unsigned int get_nominal_index(void) +{ + return powernv_pstate_info.max - powernv_pstate_info.nominal; +} + +/* * powernv_cpufreq_target_index: Sets the frequency corresponding to * the cpufreq table entry indexed by new_index on the cpus in the * mask policy->cpus @@ -293,6 +304,9 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy, { struct powernv_smp_call_data freq_data; + if (unlikely(rebooting) && new_index != get_nominal_index()) + return -EBUSY; + freq_data.pstate_id = powernv_freqs[new_index].driver_data; /* @@ -317,6 +331,25 @@ static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy) return cpufreq_table_validate_and_show(policy, powernv_freqs); } +static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb, + unsigned long action, void *unused) +{ + int cpu; + struct cpufreq_policy cpu_policy; + + rebooting = true; + for_each_online_cpu(cpu) { + cpufreq_get_policy(&cpu_policy, cpu); + powernv_cpufreq_target_index(&cpu_policy, get_nominal_index()); + } + + return NOTIFY_DONE; +} + +static struct notifier_block powernv_cpufreq_reboot_nb = { + .notifier_call = powernv_cpufreq_reboot_notifier, +}; + static struct cpufreq_driver powernv_cpufreq_driver = { .name = "powernv-cpufreq", .flags = CPUFREQ_CONST_LOOPS, @@ -342,12 +375,14 @@ static int __init powernv_cpufreq_init(void) return rc; } + register_reboot_notifier(&powernv_cpufreq_reboot_nb); return cpufreq_register_driver(&powernv_cpufreq_driver); } module_init(powernv_cpufreq_init); static void __exit powernv_cpufreq_exit(void) { + unregister_reboot_notifier(&powernv_cpufreq_reboot_nb); cpufreq_unregister_driver(&powernv_cpufreq_driver); } module_exit(powernv_cpufreq_exit);