Commit 6b4ebc3a authored Jun 04, 2014 by Davidlohr Bueso Committed by Linus Torvalds Jun 04, 2014

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>

parent 4f115147

mm/vmacache.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -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) {
		/*

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