Messages in this thread Patch in this message | | | From | Davidlohr Bueso <> | Subject | [PATCH 3/3] mm,vmacache: optimize overflow system-wide flushing | Date | Mon, 14 Apr 2014 16:57:21 -0700 |
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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 <oleg@redhat.com> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> --- 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
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