diff options
| author | Mathieu Desnoyers <[email protected]> | 2019-09-19 13:37:04 -0400 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2019-09-25 17:42:31 +0200 |
| commit | c6d68c1c4a4d6611fc0f8145d764226571d737ca (patch) | |
| tree | f808d18297778aa54b35e5cd6bf838b2636d2f8d /kernel | |
| parent | 19a4ff534bb09686f53800564cb977bad2177c00 (diff) | |
sched/membarrier: Skip IPIs when mm->mm_users == 1
If there is only a single mm_user for the mm, the private expedited
membarrier command can skip the IPIs, because only a single thread
is using the mm.
Signed-off-by: Mathieu Desnoyers <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Russell King - ARM Linux admin <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/membarrier.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 070cf433bb9a..fced54ad0f3d 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -145,20 +145,21 @@ static int membarrier_private_expedited(int flags) int cpu; bool fallback = false; cpumask_var_t tmpmask; + struct mm_struct *mm = current->mm; if (flags & MEMBARRIER_FLAG_SYNC_CORE) { if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) return -EINVAL; - if (!(atomic_read(¤t->mm->membarrier_state) & + if (!(atomic_read(&mm->membarrier_state) & MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY)) return -EPERM; } else { - if (!(atomic_read(¤t->mm->membarrier_state) & + if (!(atomic_read(&mm->membarrier_state) & MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY)) return -EPERM; } - if (num_online_cpus() == 1) + if (atomic_read(&mm->mm_users) == 1 || num_online_cpus() == 1) return 0; /* @@ -194,7 +195,7 @@ static int membarrier_private_expedited(int flags) continue; rcu_read_lock(); p = rcu_dereference(cpu_rq(cpu)->curr); - if (p && p->mm == current->mm) { + if (p && p->mm == mm) { if (!fallback) __cpumask_set_cpu(cpu, tmpmask); else |