On 20 December 2012 13:41, Vincent Guittot vincent.guittot@linaro.org wrote:
On 19 December 2012 11:57, Morten Rasmussen morten.rasmussen@arm.com wrote:
If I understand the new version of "sched: secure access to other CPU statistics" correctly, the effect of the patch is:
Without the patch the cpu will appear to be busy if sum/period are not coherent (sum>period). The same is true with the patch except in the case where nr_running is 0. In this particular case the cpu will appear not to be busy. I assume there is good reason why this particular case is important?
Sorry for this late reply.
It's not really more important than other but it's one case we can safely detect to prevent spurious spread of tasks. In addition, The incoherency occurs if both value are close so nr_running == 0 was the only condition that left to be tested
In any case the patch is fine by me.
Hmm... I am still confused :(
We have two patches from ARM, do let me know if i can drop these:
commit 3f1dff11ac95eda2772bef577e368bc124bfe087 Author: Morten Rasmussen morten.rasmussen@arm.com Date: Fri Nov 16 18:32:40 2012 +0000
ARM: TC2: Re-enable SD_SHARE_POWERLINE
Re-enable SD_SHARE_POWERLINE to reflect the power domains of TC2.
arch/arm/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
commit e8cceacd3913e3a3e955614bacc1bc81866bc243 Author: Liviu Dudau Liviu.Dudau@arm.com Date: Fri Nov 16 18:32:38 2012 +0000
Revert "sched: secure access to other CPU statistics"
This reverts commit 2aa14d0379cc54bc0ec44adb7a2e0ad02ae293d0.
The way this functionality is implemented is under review and the current implementation is considered not safe.
Signed-of-by: Liviu Dudau Liviu.Dudau@arm.com
kernel/sched/fair.c | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-)