diff options
| author | Rik van Riel <riel@redhat.com> | 2013-10-07 11:29:34 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-10-09 14:48:12 +0200 |
| commit | dabe1d992414a6456e60e41f1d1ad8affc6d444d (patch) | |
| tree | 213b65fbc7864687d0ea9db96d7e768b6ff587cf /kernel/sched | |
| parent | 0ec8aa00f2b4dc457836ef4e2662b02483e94fb7 (diff) | |
sched/numa: Be more careful about joining numa groups
Due to the way the pid is truncated, and tasks are moved between
CPUs by the scheduler, it is possible for the current task_numa_fault
to group together tasks that do not actually share memory together.
This patch adds a few easy sanity checks to task_numa_fault, joining
tasks together if they share the same tsk->mm, or if the fault was on
a page with an elevated mapcount, in a shared VMA.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-57-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5166b9b1af70..222c2d0b6ae2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1381,7 +1381,7 @@ static void double_lock(spinlock_t *l1, spinlock_t *l2) spin_lock_nested(l2, SINGLE_DEPTH_NESTING); } -static void task_numa_group(struct task_struct *p, int cpupid) +static void task_numa_group(struct task_struct *p, int cpupid, int flags) { struct numa_group *grp, *my_grp; struct task_struct *tsk; @@ -1439,10 +1439,16 @@ static void task_numa_group(struct task_struct *p, int cpupid) if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) goto unlock; - if (!get_numa_group(grp)) - goto unlock; + /* Always join threads in the same process. */ + if (tsk->mm == current->mm) + join = true; + + /* Simple filter to avoid false positives due to PID collisions */ + if (flags & TNF_SHARED) + join = true; - join = true; + if (join && !get_numa_group(grp)) + join = false; unlock: rcu_read_unlock(); @@ -1539,7 +1545,7 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags) } else { priv = cpupid_match_pid(p, last_cpupid); if (!priv && !(flags & TNF_NO_GROUP)) - task_numa_group(p, last_cpupid); + task_numa_group(p, last_cpupid, flags); } /* |