-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
On 06/30/2014 12:05 PM, Vincent Guittot wrote:
I have tried to understand the meaning of the condition : (this_load <= load && this_load + target_load(prev_cpu, idx) <= tl_per_task) but i failed to find a use case that can take advantage of it and i haven't found clear description in the previous commits' log. Futhermore, the comment of the condition refers to the task_hot function that was used before being replaced by the current condition: /* * This domain has SD_WAKE_AFFINE and * p is cache cold in this domain, and * there is no bad imbalance. */
If we look more deeply the below condition this_load + target_load(prev_cpu, idx) <= tl_per_task
When sync is clear, we have : tl_per_task = runnable_load_avg / nr_running this_load = max(runnable_load_avg, cpuload[idx]) target_load = max(runnable_load_avg', cpuload'[idx])
It implies that runnable_load_avg' == 0 and nr_running <= 1 in order to match the condition. This implies that runnable_load_avg == 0 too because of the condition: this_load <= load but if this _load is null, balanced is already set and the test is redundant.
If sync is set, it's not as straight forward as above (especially if cgroup are involved) but the policy should be similar as we have removed a task that's going to sleep in order to get a more accurate load and this_load values.
The current conclusion is that these additional condition don't give any benefit so we can remove them.
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org
Acked-by: Rik van Riel riel@redhat.com
- -- All rights reversed