| Message ID | 1362219013-18173-3-git-send-email-daniel.lezcano@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Sat, 2 Mar 2013, Daniel Lezcano wrote: > When a cpu goes to a deep idle state where its local timer is shutdown, > it notifies the time frame work to use the broadcast timer instead. > > Unfortunately, the broadcast device could wake up any CPU, including an > idle one which is not concerned by the wake up at all. > > This implies, in the worst case, an idle CPU will wake up to send an IPI > to another idle cpu. > > This patch solves this by setting the irq affinity to the cpu concerned > by the nearest timer event, by this way, the CPU which is wake up is > guarantee to be the one concerned by the next event and we are safe with > unnecessary wakeup for another idle CPU. > > As the irq affinity is not supported by all the archs, a flag is needed > to specify which clocksource can handle it : CLOCK_EVT_FEAT_DYNIRQ > > Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> > --- > include/linux/clockchips.h | 5 +++++ > kernel/time/tick-broadcast.c | 40 +++++++++++++++++++++++++++++++++------- > 2 files changed, 38 insertions(+), 7 deletions(-) > > diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h > index 6634652..c93e2a6 100644 > --- a/include/linux/clockchips.h > +++ b/include/linux/clockchips.h > @@ -55,6 +55,11 @@ enum clock_event_nofitiers { > #define CLOCK_EVT_FEAT_C3STOP 0x000008 > #define CLOCK_EVT_FEAT_DUMMY 0x000010 > > +/* > + * Clock event device can set its irq affinity dynamically > + */ > +#define CLOCK_EVT_FEAT_DYNIRQ 0x000020 > + > /** > * struct clock_event_device - clock event device descriptor > * @event_handler: Assigned by the framework to be called by the low > diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c > index 6197ac0..9ca8ff5 100644 > --- a/kernel/time/tick-broadcast.c > +++ b/kernel/time/tick-broadcast.c > @@ -406,13 +406,37 @@ struct cpumask *tick_get_broadcast_oneshot_mask(void) > return to_cpumask(tick_broadcast_oneshot_mask); > } > > -static int tick_broadcast_set_event(struct clock_event_device *bc, > +/* > + * Set broadcast interrupt affinity > + */ > +static void tick_broadcast_set_affinity(struct clock_event_device *bc, > + const struct cpumask *cpumask) > +{ > + if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) > + return; > + > + if (cpumask_equal(bc->cpumask, cpumask)) > + return; > + > + bc->cpumask = cpumask; This breaks with CONFIG_CPUMASK_OFFSTACK=y. cpumask_copy() is your friend! Thanks, tglx
On 03/05/2013 09:40 PM, Thomas Gleixner wrote: > On Sat, 2 Mar 2013, Daniel Lezcano wrote: >> When a cpu goes to a deep idle state where its local timer is shutdown, >> it notifies the time frame work to use the broadcast timer instead. >> >> Unfortunately, the broadcast device could wake up any CPU, including an >> idle one which is not concerned by the wake up at all. >> >> This implies, in the worst case, an idle CPU will wake up to send an IPI >> to another idle cpu. >> >> This patch solves this by setting the irq affinity to the cpu concerned >> by the nearest timer event, by this way, the CPU which is wake up is >> guarantee to be the one concerned by the next event and we are safe with >> unnecessary wakeup for another idle CPU. >> >> As the irq affinity is not supported by all the archs, a flag is needed >> to specify which clocksource can handle it : CLOCK_EVT_FEAT_DYNIRQ >> >> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> >> --- >> include/linux/clockchips.h | 5 +++++ >> kernel/time/tick-broadcast.c | 40 +++++++++++++++++++++++++++++++++------- >> 2 files changed, 38 insertions(+), 7 deletions(-) >> >> diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h >> index 6634652..c93e2a6 100644 >> --- a/include/linux/clockchips.h >> +++ b/include/linux/clockchips.h >> @@ -55,6 +55,11 @@ enum clock_event_nofitiers { >> #define CLOCK_EVT_FEAT_C3STOP 0x000008 >> #define CLOCK_EVT_FEAT_DUMMY 0x000010 >> >> +/* >> + * Clock event device can set its irq affinity dynamically >> + */ >> +#define CLOCK_EVT_FEAT_DYNIRQ 0x000020 >> + >> /** >> * struct clock_event_device - clock event device descriptor >> * @event_handler: Assigned by the framework to be called by the low >> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c >> index 6197ac0..9ca8ff5 100644 >> --- a/kernel/time/tick-broadcast.c >> +++ b/kernel/time/tick-broadcast.c >> @@ -406,13 +406,37 @@ struct cpumask *tick_get_broadcast_oneshot_mask(void) >> return to_cpumask(tick_broadcast_oneshot_mask); >> } >> >> -static int tick_broadcast_set_event(struct clock_event_device *bc, >> +/* >> + * Set broadcast interrupt affinity >> + */ >> +static void tick_broadcast_set_affinity(struct clock_event_device *bc, >> + const struct cpumask *cpumask) >> +{ >> + if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) >> + return; >> + >> + if (cpumask_equal(bc->cpumask, cpumask)) >> + return; >> + >> + bc->cpumask = cpumask; > > This breaks with CONFIG_CPUMASK_OFFSTACK=y. cpumask_copy() is your friend! This instruction copies the pointer, not the cpumask content. bc->cpumask is defined as a const struct cpumask * and is used to copy a cpumask pointer not the content. The cpumask parameter is a pointer to a global cpumask provided by the cpumask_of macro. But to be in the safe side, I compiled tested with CONFIG_CPUMASK_OFFSTACK=y without problem. Did I missed something ? Thanks -- Daniel > -- > 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 >
On Wed, 6 Mar 2013, Daniel Lezcano wrote: > On 03/05/2013 09:40 PM, Thomas Gleixner wrote: > > On Sat, 2 Mar 2013, Daniel Lezcano wrote: > >> When a cpu goes to a deep idle state where its local timer is shutdown, > >> it notifies the time frame work to use the broadcast timer instead. > >> > >> Unfortunately, the broadcast device could wake up any CPU, including an > >> idle one which is not concerned by the wake up at all. > >> > >> This implies, in the worst case, an idle CPU will wake up to send an IPI > >> to another idle cpu. > >> > >> This patch solves this by setting the irq affinity to the cpu concerned > >> by the nearest timer event, by this way, the CPU which is wake up is > >> guarantee to be the one concerned by the next event and we are safe with > >> unnecessary wakeup for another idle CPU. > >> > >> As the irq affinity is not supported by all the archs, a flag is needed > >> to specify which clocksource can handle it : CLOCK_EVT_FEAT_DYNIRQ > >> > >> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> > >> --- > >> include/linux/clockchips.h | 5 +++++ > >> kernel/time/tick-broadcast.c | 40 +++++++++++++++++++++++++++++++++------- > >> 2 files changed, 38 insertions(+), 7 deletions(-) > >> > >> diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h > >> index 6634652..c93e2a6 100644 > >> --- a/include/linux/clockchips.h > >> +++ b/include/linux/clockchips.h > >> @@ -55,6 +55,11 @@ enum clock_event_nofitiers { > >> #define CLOCK_EVT_FEAT_C3STOP 0x000008 > >> #define CLOCK_EVT_FEAT_DUMMY 0x000010 > >> > >> +/* > >> + * Clock event device can set its irq affinity dynamically > >> + */ > >> +#define CLOCK_EVT_FEAT_DYNIRQ 0x000020 > >> + > >> /** > >> * struct clock_event_device - clock event device descriptor > >> * @event_handler: Assigned by the framework to be called by the low > >> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c > >> index 6197ac0..9ca8ff5 100644 > >> --- a/kernel/time/tick-broadcast.c > >> +++ b/kernel/time/tick-broadcast.c > >> @@ -406,13 +406,37 @@ struct cpumask *tick_get_broadcast_oneshot_mask(void) > >> return to_cpumask(tick_broadcast_oneshot_mask); > >> } > >> > >> -static int tick_broadcast_set_event(struct clock_event_device *bc, > >> +/* > >> + * Set broadcast interrupt affinity > >> + */ > >> +static void tick_broadcast_set_affinity(struct clock_event_device *bc, > >> + const struct cpumask *cpumask) > >> +{ > >> + if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) > >> + return; > >> + > >> + if (cpumask_equal(bc->cpumask, cpumask)) > >> + return; > >> + > >> + bc->cpumask = cpumask; > > > > This breaks with CONFIG_CPUMASK_OFFSTACK=y. cpumask_copy() is your friend! > > This instruction copies the pointer, not the cpumask content. > > bc->cpumask is defined as a const struct cpumask * and is used to copy a > cpumask pointer not the content. > > The cpumask parameter is a pointer to a global cpumask provided by the > cpumask_of macro. > > But to be in the safe side, I compiled tested with > CONFIG_CPUMASK_OFFSTACK=y without problem. > > Did I missed something ? No, I misinterpreted the patch. Assigning a pointer is safe. Thanks, tglx
On 03/06/2013 10:48 AM, Thomas Gleixner wrote: > On Wed, 6 Mar 2013, Daniel Lezcano wrote: >> On 03/05/2013 09:40 PM, Thomas Gleixner wrote: >>> On Sat, 2 Mar 2013, Daniel Lezcano wrote: >>>> When a cpu goes to a deep idle state where its local timer is shutdown, >>>> it notifies the time frame work to use the broadcast timer instead. >>>> >>>> Unfortunately, the broadcast device could wake up any CPU, including an >>>> idle one which is not concerned by the wake up at all. >>>> >>>> This implies, in the worst case, an idle CPU will wake up to send an IPI >>>> to another idle cpu. >>>> >>>> This patch solves this by setting the irq affinity to the cpu concerned >>>> by the nearest timer event, by this way, the CPU which is wake up is >>>> guarantee to be the one concerned by the next event and we are safe with >>>> unnecessary wakeup for another idle CPU. >>>> >>>> As the irq affinity is not supported by all the archs, a flag is needed >>>> to specify which clocksource can handle it : CLOCK_EVT_FEAT_DYNIRQ >>>> >>>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> >>>> --- >>>> include/linux/clockchips.h | 5 +++++ >>>> kernel/time/tick-broadcast.c | 40 +++++++++++++++++++++++++++++++++------- >>>> 2 files changed, 38 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h >>>> index 6634652..c93e2a6 100644 >>>> --- a/include/linux/clockchips.h >>>> +++ b/include/linux/clockchips.h >>>> @@ -55,6 +55,11 @@ enum clock_event_nofitiers { >>>> #define CLOCK_EVT_FEAT_C3STOP 0x000008 >>>> #define CLOCK_EVT_FEAT_DUMMY 0x000010 >>>> >>>> +/* >>>> + * Clock event device can set its irq affinity dynamically >>>> + */ >>>> +#define CLOCK_EVT_FEAT_DYNIRQ 0x000020 >>>> + >>>> /** >>>> * struct clock_event_device - clock event device descriptor >>>> * @event_handler: Assigned by the framework to be called by the low >>>> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c >>>> index 6197ac0..9ca8ff5 100644 >>>> --- a/kernel/time/tick-broadcast.c >>>> +++ b/kernel/time/tick-broadcast.c >>>> @@ -406,13 +406,37 @@ struct cpumask *tick_get_broadcast_oneshot_mask(void) >>>> return to_cpumask(tick_broadcast_oneshot_mask); >>>> } >>>> >>>> -static int tick_broadcast_set_event(struct clock_event_device *bc, >>>> +/* >>>> + * Set broadcast interrupt affinity >>>> + */ >>>> +static void tick_broadcast_set_affinity(struct clock_event_device *bc, >>>> + const struct cpumask *cpumask) >>>> +{ >>>> + if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) >>>> + return; >>>> + >>>> + if (cpumask_equal(bc->cpumask, cpumask)) >>>> + return; >>>> + >>>> + bc->cpumask = cpumask; >>> >>> This breaks with CONFIG_CPUMASK_OFFSTACK=y. cpumask_copy() is your friend! >> >> This instruction copies the pointer, not the cpumask content. >> >> bc->cpumask is defined as a const struct cpumask * and is used to copy a >> cpumask pointer not the content. >> >> The cpumask parameter is a pointer to a global cpumask provided by the >> cpumask_of macro. >> >> But to be in the safe side, I compiled tested with >> CONFIG_CPUMASK_OFFSTACK=y without problem. >> >> Did I missed something ? > > No, I misinterpreted the patch. Assigning a pointer is safe. Ok, thanks anyway for reviewing the patch. Do you think it is acceptable for upstreaming ? -- Daniel <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
On 03/06/2013 10:48 AM, Thomas Gleixner wrote: > On Wed, 6 Mar 2013, Daniel Lezcano wrote: >> On 03/05/2013 09:40 PM, Thomas Gleixner wrote: >>> On Sat, 2 Mar 2013, Daniel Lezcano wrote: >>>> When a cpu goes to a deep idle state where its local timer is shutdown, >>>> it notifies the time frame work to use the broadcast timer instead. >>>> >>>> Unfortunately, the broadcast device could wake up any CPU, including an >>>> idle one which is not concerned by the wake up at all. >>>> >>>> This implies, in the worst case, an idle CPU will wake up to send an IPI >>>> to another idle cpu. >>>> >>>> This patch solves this by setting the irq affinity to the cpu concerned >>>> by the nearest timer event, by this way, the CPU which is wake up is >>>> guarantee to be the one concerned by the next event and we are safe with >>>> unnecessary wakeup for another idle CPU. >>>> >>>> As the irq affinity is not supported by all the archs, a flag is needed >>>> to specify which clocksource can handle it : CLOCK_EVT_FEAT_DYNIRQ >>>> >>>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> >>>> --- >>>> include/linux/clockchips.h | 5 +++++ >>>> kernel/time/tick-broadcast.c | 40 +++++++++++++++++++++++++++++++++------- >>>> 2 files changed, 38 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h >>>> index 6634652..c93e2a6 100644 >>>> --- a/include/linux/clockchips.h >>>> +++ b/include/linux/clockchips.h >>>> @@ -55,6 +55,11 @@ enum clock_event_nofitiers { >>>> #define CLOCK_EVT_FEAT_C3STOP 0x000008 >>>> #define CLOCK_EVT_FEAT_DUMMY 0x000010 >>>> >>>> +/* >>>> + * Clock event device can set its irq affinity dynamically >>>> + */ >>>> +#define CLOCK_EVT_FEAT_DYNIRQ 0x000020 >>>> + >>>> /** >>>> * struct clock_event_device - clock event device descriptor >>>> * @event_handler: Assigned by the framework to be called by the low >>>> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c >>>> index 6197ac0..9ca8ff5 100644 >>>> --- a/kernel/time/tick-broadcast.c >>>> +++ b/kernel/time/tick-broadcast.c >>>> @@ -406,13 +406,37 @@ struct cpumask *tick_get_broadcast_oneshot_mask(void) >>>> return to_cpumask(tick_broadcast_oneshot_mask); >>>> } >>>> >>>> -static int tick_broadcast_set_event(struct clock_event_device *bc, >>>> +/* >>>> + * Set broadcast interrupt affinity >>>> + */ >>>> +static void tick_broadcast_set_affinity(struct clock_event_device *bc, >>>> + const struct cpumask *cpumask) >>>> +{ >>>> + if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) >>>> + return; >>>> + >>>> + if (cpumask_equal(bc->cpumask, cpumask)) >>>> + return; >>>> + >>>> + bc->cpumask = cpumask; >>> >>> This breaks with CONFIG_CPUMASK_OFFSTACK=y. cpumask_copy() is your friend! >> >> This instruction copies the pointer, not the cpumask content. >> >> bc->cpumask is defined as a const struct cpumask * and is used to copy a >> cpumask pointer not the content. >> >> The cpumask parameter is a pointer to a global cpumask provided by the >> cpumask_of macro. >> >> But to be in the safe side, I compiled tested with >> CONFIG_CPUMASK_OFFSTACK=y without problem. Hi Thomas, thanks for merging the patch 1 and 2. I was wondering if it would be possible to take the 3/4 and 4/4 otherwise the flag dependency will prevent to send those to the maintainer's tree until they gain visibility on it.
On Fri, 8 Mar 2013, Daniel Lezcano wrote: > On 03/06/2013 10:48 AM, Thomas Gleixner wrote: > I was wondering if it would be possible to take the 3/4 and 4/4 > otherwise the flag dependency will prevent to send those to the > maintainer's tree until they gain visibility on it. I can take them with the ack of arm soc folks. Thanks, tglx
On Friday 08 March 2013, Thomas Gleixner wrote: > On Fri, 8 Mar 2013, Daniel Lezcano wrote: > > On 03/06/2013 10:48 AM, Thomas Gleixner wrote: > > I was wondering if it would be possible to take the 3/4 and 4/4 > > otherwise the flag dependency will prevent to send those to the > > maintainer's tree until they gain visibility on it. > > I can take them with the ack of arm soc folks. Sounds good, Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h index 6634652..c93e2a6 100644 --- a/include/linux/clockchips.h +++ b/include/linux/clockchips.h @@ -55,6 +55,11 @@ enum clock_event_nofitiers { #define CLOCK_EVT_FEAT_C3STOP 0x000008 #define CLOCK_EVT_FEAT_DUMMY 0x000010 +/* + * Clock event device can set its irq affinity dynamically + */ +#define CLOCK_EVT_FEAT_DYNIRQ 0x000020 + /** * struct clock_event_device - clock event device descriptor * @event_handler: Assigned by the framework to be called by the low diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 6197ac0..9ca8ff5 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -406,13 +406,37 @@ struct cpumask *tick_get_broadcast_oneshot_mask(void) return to_cpumask(tick_broadcast_oneshot_mask); } -static int tick_broadcast_set_event(struct clock_event_device *bc, +/* + * Set broadcast interrupt affinity + */ +static void tick_broadcast_set_affinity(struct clock_event_device *bc, + const struct cpumask *cpumask) +{ + if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) + return; + + if (cpumask_equal(bc->cpumask, cpumask)) + return; + + bc->cpumask = cpumask; + irq_set_affinity(bc->irq, bc->cpumask); +} + +static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu, ktime_t expires, int force) { + int ret; + if (bc->mode != CLOCK_EVT_MODE_ONESHOT) clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); - return clockevents_program_event(bc, expires, force); + ret = clockevents_program_event(bc, expires, force); + if (ret) + return ret; + + tick_broadcast_set_affinity(bc, cpumask_of(cpu)); + + return 0; } int tick_resume_broadcast_oneshot(struct clock_event_device *bc) @@ -441,7 +465,7 @@ static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) { struct tick_device *td; ktime_t now, next_event; - int cpu; + int cpu, next_cpu; raw_spin_lock(&tick_broadcast_lock); again: @@ -454,8 +478,10 @@ again: td = &per_cpu(tick_cpu_device, cpu); if (td->evtdev->next_event.tv64 <= now.tv64) cpumask_set_cpu(cpu, to_cpumask(tmpmask)); - else if (td->evtdev->next_event.tv64 < next_event.tv64) + else if (td->evtdev->next_event.tv64 < next_event.tv64) { next_event.tv64 = td->evtdev->next_event.tv64; + next_cpu = cpu; + } } /* @@ -478,7 +504,7 @@ again: * Rearm the broadcast device. If event expired, * repeat the above */ - if (tick_broadcast_set_event(dev, next_event, 0)) + if (tick_broadcast_set_event(dev, next_cpu, next_event, 0)) goto again; } raw_spin_unlock(&tick_broadcast_lock); @@ -521,7 +547,7 @@ void tick_broadcast_oneshot_control(unsigned long reason) cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask()); clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); if (dev->next_event.tv64 < bc->next_event.tv64) - tick_broadcast_set_event(bc, dev->next_event, 1); + tick_broadcast_set_event(bc, cpu, dev->next_event, 1); } } else { if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) { @@ -590,7 +616,7 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); tick_broadcast_init_next_event(to_cpumask(tmpmask), tick_next_period); - tick_broadcast_set_event(bc, tick_next_period, 1); + tick_broadcast_set_event(bc, cpu, tick_next_period, 1); } else bc->next_event.tv64 = KTIME_MAX; } else {
When a cpu goes to a deep idle state where its local timer is shutdown, it notifies the time frame work to use the broadcast timer instead. Unfortunately, the broadcast device could wake up any CPU, including an idle one which is not concerned by the wake up at all. This implies, in the worst case, an idle CPU will wake up to send an IPI to another idle cpu. This patch solves this by setting the irq affinity to the cpu concerned by the nearest timer event, by this way, the CPU which is wake up is guarantee to be the one concerned by the next event and we are safe with unnecessary wakeup for another idle CPU. As the irq affinity is not supported by all the archs, a flag is needed to specify which clocksource can handle it : CLOCK_EVT_FEAT_DYNIRQ Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> --- include/linux/clockchips.h | 5 +++++ kernel/time/tick-broadcast.c | 40 +++++++++++++++++++++++++++++++++------- 2 files changed, 38 insertions(+), 7 deletions(-)