sched_can_stop_tick() was using 7 spaces instead of 8 spaces or a 'tab' at the beginning of each line. Which doesn't align with the Coding Guidelines.
Also it removes the *rq variable as it was used at only one place and hence we can directly use this_rq() instead.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- I don't think rq = tihs_rq() has to be done before smp_mb(), in case yes sorry for this patch :(
kernel/sched/core.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 268a45e..13299c5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -666,18 +666,14 @@ static inline bool got_nohz_idle_kick(void) #ifdef CONFIG_NO_HZ_FULL bool sched_can_stop_tick(void) { - struct rq *rq; - - rq = this_rq(); - - /* Make sure rq->nr_running update is visible after the IPI */ - smp_rmb(); + /* Make sure rq->nr_running update is visible after the IPI */ + smp_rmb();
- /* More than one running task need preemption */ - if (rq->nr_running > 1) - return false; + /* More than one running task need preemption */ + if (this_rq()->nr_running > 1) + return false;
- return true; + return true; } #endif /* CONFIG_NO_HZ_FULL */
On Mon, Apr 14, 2014 at 09:47:41PM +0530, Viresh Kumar wrote:
sched_can_stop_tick() was using 7 spaces instead of 8 spaces or a 'tab' at the beginning of each line. Which doesn't align with the Coding Guidelines.
Also it removes the *rq variable as it was used at only one place and hence we can directly use this_rq() instead.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
I don't think rq = tihs_rq() has to be done before smp_mb(), in case yes sorry for this patch :(
kernel/sched/core.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 268a45e..13299c5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -666,18 +666,14 @@ static inline bool got_nohz_idle_kick(void) #ifdef CONFIG_NO_HZ_FULL bool sched_can_stop_tick(void) {
- /* Make sure rq->nr_running update is visible after the IPI */
- smp_rmb();
- /* More than one running task need preemption */
- if (this_rq()->nr_running > 1)
return false;
- return true;
} #endif /* CONFIG_NO_HZ_FULL */
AFAICT the smp_rmb() is entirely spurious, arch interrupts should ensure consistency on their own. That is:
CPU 0 CPU 1
[w] X = 1 IPI 1 <int> [r] r = X
Should act as if there was a full memory barrier, making it so that the read on CPU1 observes the write on CPU0.
On Mon, Apr 14, 2014 at 08:38:38PM +0200, Peter Zijlstra wrote:
On Mon, Apr 14, 2014 at 09:47:41PM +0530, Viresh Kumar wrote:
sched_can_stop_tick() was using 7 spaces instead of 8 spaces or a 'tab' at the beginning of each line. Which doesn't align with the Coding Guidelines.
Also it removes the *rq variable as it was used at only one place and hence we can directly use this_rq() instead.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
I don't think rq = tihs_rq() has to be done before smp_mb(), in case yes sorry for this patch :(
kernel/sched/core.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 268a45e..13299c5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -666,18 +666,14 @@ static inline bool got_nohz_idle_kick(void) #ifdef CONFIG_NO_HZ_FULL bool sched_can_stop_tick(void) {
- /* Make sure rq->nr_running update is visible after the IPI */
- smp_rmb();
- /* More than one running task need preemption */
- if (this_rq()->nr_running > 1)
return false;
- return true;
} #endif /* CONFIG_NO_HZ_FULL */
AFAICT the smp_rmb() is entirely spurious, arch interrupts should ensure consistency on their own. That is:
CPU 0 CPU 1
[w] X = 1 IPI 1 <int> [r] r = X
Should act as if there was a full memory barrier, making it so that the read on CPU1 observes the write on CPU0.
Right, I have a pending patch for that: https://git.kernel.org/cgit/linux/kernel/git/frederic/linux-dynticks.git/com...
On 15 April 2014 04:18, Frederic Weisbecker fweisbec@gmail.com wrote:
Right, I have a pending patch for that:
https://git.kernel.org/cgit/linux/kernel/git/frederic/linux-dynticks.git/com...
Cool!! I will rebase my patch over yours and resend.
linaro-kernel@lists.linaro.org
-
Frederic Weisbecker -
Peter Zijlstra -
Viresh Kumar