Messages in this thread |  | | Date | Thu, 12 Dec 2013 13:07:45 +0100 | From | Daniel Lezcano <> | Subject | Re: [PATCH 1/2] time: Serialize calls to 'clockevents_update_freq' in the timing core |
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On 12/11/2013 09:09 PM, Sören Brinkmann wrote: > Hi Daniel, > > On Wed, Dec 11, 2013 at 03:32:57PM +0100, Daniel Lezcano wrote: >> On 12/10/2013 01:34 AM, Soren Brinkmann wrote: >>> From: Thomas Gleixner <tglx@linutronix.de> >>> >>> We can identify the broadcast device in the core and serialize all >>> callers including interrupts on a different CPU against the update. >>> Also, disabling interrupts is moved into the core allowing callers to >>> leave interrutps enabled when calling clockevents_update_freq(). >>> >>> Cc: Thomas Gleixner <tglx@linutronix.de> >>> Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> >>> --- >>> kernel/time/clockevents.c | 29 ++++++++++++++++++++++------- >>> kernel/time/tick-broadcast.c | 25 +++++++++++++++++++------ >>> kernel/time/tick-internal.h | 4 ++++ >>> 3 files changed, 45 insertions(+), 13 deletions(-) >>> >>> diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c >>> index 086ad6043bcb..641d91003a45 100644 >>> --- a/kernel/time/clockevents.c >>> +++ b/kernel/time/clockevents.c >>> @@ -439,6 +439,16 @@ void clockevents_config_and_register(struct clock_event_device *dev, >>> } >>> EXPORT_SYMBOL_GPL(clockevents_config_and_register); >>> >>> +int __clockevents_update_freq(struct clock_event_device *dev, u32 freq) >>> +{ >>> + clockevents_config(dev, freq); >>> + >>> + if (dev->mode != CLOCK_EVT_MODE_ONESHOT) >>> + return 0; >>> + >>> + return clockevents_program_event(dev, dev->next_event, false); >>> +} >>> + >> >> ./arch/arm/kernel/smp_twd.c should be modified to call >> __clockevents_update_freq instead of clockevents_update_freq, no ? > > IIUC, the __-version is only for timer core internal usage and not an > exported interface. Doesn't the non-__ version work for the twd? > I don't see issues on my Zynq platform with these patches.
I don't think there is an issue but if we can rid of the extra code added in clockevents_update_freq with this patch for twd, it would make sense. The __-version means the function is lockless and there is a function without '__' in the name with the lock.
> Another side note regarding the twd: Shouldn't we set the > CLOCK_EVT_FEAT_PERCPU flag we introduced recently for that timer?
Yes.
There will be some fun with the patchset http://lwn.net/Articles/566270/ where the local timer could be used as a broadcast timer.
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