mm,vmacache: optimize overflow system-wide flushing

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.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Davidlohr Bueso 2014-06-04 16:06:47 -07:00 committed by Linus Torvalds
parent 4f115147ff
commit 6b4ebc3a90

View File

@ -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) {
/*