For single threaded workloads, we can avoid flushing and iterating through the entire list of tasks, making the whole function a lot faster, requiring only a single atomic read for the mm_users.
Suggested-by: Oleg Nesterov <[email protected]> Signed-off-by: Davidlohr Bueso <[email protected]> --- mm/vmacache.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/vmacache.c b/mm/vmacache.c index e167da2..61c38ae 100644 --- a/mm/vmacache.c +++ b/mm/vmacache.c @@ -17,6 +17,16 @@ void vmacache_flush_all(struct mm_struct *mm) { struct task_struct *g, *p; + /* + * Single threaded tasks need not iterate the entire + * list of process. We can avoid the flushing as well + * since the mm's seqnum was increased and don't have + * to worry about other threads' seqnum. Current's + * flush will occur upon the next lookup. + */ + if (atomic_read(&mm->mm_users) == 1) + return; + rcu_read_lock(); for_each_process_thread(g, p) { /* -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
