Messages in this thread Patch in this message | | | From | Srikar Dronamraju <> | Subject | [PATCH 09/19] sched/numa: Modify migrate_swap to accept additional params | Date | Mon, 4 Jun 2018 15:30:18 +0530 |
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There are checks in migrate_swap_stop that check if the task/cpu combination is as per migrate_swap_arg before migrating.
However atleast one of the two tasks to be swapped by migrate_swap could have migrated to a completely different cpu before updating the migrate_swap_arg. The new cpu where the task is currently running could be a different node too. If the task has migrated, numa balancer might end up placing a task in a wrong node. Instead of achieving node consolidation, it may end up spreading the load across nodes.
To avoid that pass the cpus as additional parameters.
While here, place migrate_swap under CONFIG_NUMA_BALANCING.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> --- kernel/sched/core.c | 9 ++++++--- kernel/sched/fair.c | 3 ++- kernel/sched/sched.h | 3 ++- 3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 092f7c4..68849c2 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1178,6 +1178,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) __set_task_cpu(p, new_cpu); } +#ifdef CONFIG_NUMA_BALANCING static void __migrate_swap_task(struct task_struct *p, int cpu) { if (task_on_rq_queued(p)) { @@ -1259,16 +1260,17 @@ static int migrate_swap_stop(void *data) /* * Cross migrate two tasks */ -int migrate_swap(struct task_struct *cur, struct task_struct *p) +int migrate_swap(struct task_struct *cur, struct task_struct *p, + int target_cpu, int curr_cpu) { struct migration_swap_arg arg; int ret = -EINVAL; arg = (struct migration_swap_arg){ .src_task = cur, - .src_cpu = task_cpu(cur), + .src_cpu = curr_cpu, .dst_task = p, - .dst_cpu = task_cpu(p), + .dst_cpu = target_cpu, }; if (arg.src_cpu == arg.dst_cpu) @@ -1293,6 +1295,7 @@ int migrate_swap(struct task_struct *cur, struct task_struct *p) out: return ret; } +#endif /* CONFIG_NUMA_BALANCING */ /* * wait_task_inactive - wait for a thread to unschedule. diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 35c4a75..46d773c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1810,7 +1810,8 @@ static int task_numa_migrate(struct task_struct *p) return ret; } - ret = migrate_swap(p, env.best_task); + ret = migrate_swap(p, env.best_task, env.best_cpu, env.src_cpu); + if (ret != 0) trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); put_task_struct(env.best_task); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 15750c2..211841e 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1068,7 +1068,8 @@ enum numa_faults_stats { }; extern void sched_setnuma(struct task_struct *p, int node); extern int migrate_task_to(struct task_struct *p, int cpu); -extern int migrate_swap(struct task_struct *, struct task_struct *); +extern int migrate_swap(struct task_struct *p, struct task_struct *t, + int cpu, int scpu); #endif /* CONFIG_NUMA_BALANCING */ #ifdef CONFIG_SMP -- 1.8.3.1
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