From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m6.gw.fujitsu.co.jp ([10.0.50.76]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id m9R3Esw9009208 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 27 Oct 2008 12:14:54 +0900 Received: from smail (m6 [127.0.0.1]) by outgoing.m6.gw.fujitsu.co.jp (Postfix) with ESMTP id 269F153C125 for ; Mon, 27 Oct 2008 12:14:54 +0900 (JST) Received: from s8.gw.fujitsu.co.jp (s8.gw.fujitsu.co.jp [10.0.50.98]) by m6.gw.fujitsu.co.jp (Postfix) with ESMTP id EF44F240049 for ; Mon, 27 Oct 2008 12:14:53 +0900 (JST) Received: from s8.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s8.gw.fujitsu.co.jp (Postfix) with ESMTP id D7CE31DB8041 for ; Mon, 27 Oct 2008 12:14:53 +0900 (JST) Received: from ml10.s.css.fujitsu.com (ml10.s.css.fujitsu.com [10.249.87.100]) by s8.gw.fujitsu.co.jp (Postfix) with ESMTP id 82A8F1DB8038 for ; Mon, 27 Oct 2008 12:14:53 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [RFC][PATCH] lru_add_drain_all() don't use schedule_on_each_cpu() In-Reply-To: <1225037872.32713.22.camel@twins> References: <2f11576a0810260851h15cb7e1ahb454b70a2e99e1a8@mail.gmail.com> <1225037872.32713.22.camel@twins> Message-Id: <20081027120405.1B45.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Mon, 27 Oct 2008 12:14:52 +0900 (JST) Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: kosaki.motohiro@jp.fujitsu.com, Heiko Carstens , Nick Piggin , linux-kernel@vger.kernel.org, Hugh Dickins , Andrew Morton , Linus Torvalds , Rik van Riel , Lee Schermerhorn , linux-mm@kvack.org, Christoph Lameter , Gautham Shenoy , Oleg Nesterov , Rusty Russell , mpm List-ID: > Right, and would be about 4k+sizeof(task_struct), some people might be > bothered, but most won't care. > > > Perhaps, I misunderstand your intension. so can you point your > > previous discussion url? > > my google skillz fail me, but once in a while people complain that we > have too many kernel threads. > > Anyway, if we can re-use this per-cpu workqueue for more goals, I guess > there is even less of an objection. In general, you are right. but this is special case. mmap_sem is really widely used various subsystem and drivers. (because page fault via copy_user introduce to depend on mmap_sem) Then, any work-queue reu-sing can cause similar dead-lock easily. So I think we have two choices (nick explained it at this thread). (1) own workqueue (the patch) (2) avoid lru_add_drain_all completely if you really strongly hate (1), we should target to (2) IMO. Thought? -- 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