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@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx>
---
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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