From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id F0ED86B004D for ; Tue, 6 Oct 2009 12:33:32 -0400 (EDT) Received: from localhost (smtp.ultrahosting.com [127.0.0.1]) by smtp.ultrahosting.com (Postfix) with ESMTP id 889B682C3AD for ; Tue, 6 Oct 2009 12:37:11 -0400 (EDT) Received: from smtp.ultrahosting.com ([74.213.174.253]) by localhost (smtp.ultrahosting.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 48WWk-LKcBCK for ; Tue, 6 Oct 2009 12:37:11 -0400 (EDT) Received: from gentwo.org (unknown [74.213.171.31]) by smtp.ultrahosting.com (Postfix) with ESMTP id 42EB182C280 for ; Tue, 6 Oct 2009 12:36:57 -0400 (EDT) Date: Tue, 6 Oct 2009 12:27:27 -0400 (EDT) From: Christoph Lameter Subject: Re: [PATCH 2/2] mlock use lru_add_drain_all_async() In-Reply-To: <20091006114052.5FAA.A69D9226@jp.fujitsu.com> Message-ID: References: <20091006112803.5FA5.A69D9226@jp.fujitsu.com> <20091006114052.5FAA.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: LKML , linux-mm , Andrew Morton , Peter Zijlstra , Oleg Nesterov List-ID: On Tue, 6 Oct 2009, KOSAKI Motohiro wrote: > Suppose you have 2 cpus, cpu1 is busy doing a SCHED_FIFO-99 while(1), > cpu0 does mlock()->lru_add_drain_all(), which does > schedule_on_each_cpu(), which then waits for all cpus to complete the > work. Except that cpu1, which is busy with the RT task, will never run > keventd until the RT load goes away. > > This is not so much an actual deadlock as a serious starvation case. > > Actually, mlock() doesn't need to wait to finish lru_add_drain_all(). > Thus, this patch replace it with lru_add_drain_all_async(). Ok so this will queue up lots of events for the cpu doing a RT task. If the RT task is continuous then they will be queued there forever? -- 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