From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f178.google.com (mail-pd0-f178.google.com [209.85.192.178]) by kanga.kvack.org (Postfix) with ESMTP id B57E26B0037 for ; Mon, 14 Apr 2014 19:57:30 -0400 (EDT) Received: by mail-pd0-f178.google.com with SMTP id x10so8722905pdj.9 for ; Mon, 14 Apr 2014 16:57:30 -0700 (PDT) Received: from g2t2353.austin.hp.com (g2t2353.austin.hp.com. [15.217.128.52]) by mx.google.com with ESMTPS id py5si3626595pbc.400.2014.04.14.16.57.29 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 14 Apr 2014 16:57:29 -0700 (PDT) From: Davidlohr Bueso Subject: [PATCH 3/3] mm,vmacache: optimize overflow system-wide flushing Date: Mon, 14 Apr 2014 16:57:21 -0700 Message-Id: <1397519841-24847-4-git-send-email-davidlohr@hp.com> In-Reply-To: <1397519841-24847-1-git-send-email-davidlohr@hp.com> References: <1397519841-24847-1-git-send-email-davidlohr@hp.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, davidlohr@hp.com, aswin@hp.com 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 Signed-off-by: Davidlohr Bueso --- 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org