Messages in this thread Patch in this message |  | | From | Alex Shi <> | Subject | [patch v4 03/18] sched: fix find_idlest_group mess logical | Date | Thu, 24 Jan 2013 11:06:45 +0800 |
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There is 4 situations in the function: 1, no task allowed group; so min_load = ULONG_MAX, this_load = 0, idlest = NULL 2, only local group task allowed; so min_load = ULONG_MAX, this_load assigned, idlest = NULL 3, only non-local task group allowed; so min_load assigned, this_load = 0, idlest != NULL 4, local group + another group are task allowed. so min_load assigned, this_load assigned, idlest != NULL
Current logical will return NULL in first 3 kinds of scenarios. And still return NULL, if idlest group is heavier then the local group in the 4th situation.
Actually, I thought groups in situation 2,3 are also eligible to host the task. And in 4th situation, agree to bias toward local group. So, has this patch.
Signed-off-by: Alex Shi <alex.shi@intel.com> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> --- kernel/sched/fair.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6d3a95d..3c7b09a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3181,6 +3181,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu, int load_idx) { struct sched_group *idlest = NULL, *group = sd->groups; + struct sched_group *this_group = NULL; unsigned long min_load = ULONG_MAX, this_load = 0; int imbalance = 100 + (sd->imbalance_pct-100)/2; @@ -3215,14 +3216,19 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, if (local_group) { this_load = avg_load; - } else if (avg_load < min_load) { + this_group = group; + } + if (avg_load < min_load) { min_load = avg_load; idlest = group; } } while (group = group->next, group != sd->groups); - if (!idlest || 100*this_load < imbalance*min_load) - return NULL; + if (this_group && idlest != this_group) + /* Bias toward our group again */ + if (100*this_load < imbalance*min_load) + idlest = this_group; + return idlest; } -- 1.7.12
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