From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id DC5F76B0099 for ; Thu, 14 Jan 2010 02:02:46 -0500 (EST) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o0E72hxg014421 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Thu, 14 Jan 2010 16:02:44 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id B088E45DE79 for ; Thu, 14 Jan 2010 16:02:43 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 820B145DE4D for ; Thu, 14 Jan 2010 16:02:43 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 667D11DB803F for ; Thu, 14 Jan 2010 16:02:43 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 190BF1DB803A for ; Thu, 14 Jan 2010 16:02:43 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH v5] add MAP_UNLOCKED mmap flag In-Reply-To: <20100114065008.GC18808@redhat.com> References: <20100114092845.D719.A69D9226@jp.fujitsu.com> <20100114065008.GC18808@redhat.com> Message-Id: <20100114155229.6735.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Thu, 14 Jan 2010 16:02:42 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Gleb Natapov Cc: kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, akpm@linux-foundation.org List-ID: > On Thu, Jan 14, 2010 at 09:31:03AM +0900, KOSAKI Motohiro wrote: > > > If application does mlockall(MCL_FUTURE) it is no longer possible to mmap > > > file bigger than main memory or allocate big area of anonymous memory > > > in a thread safe manner. Sometimes it is desirable to lock everything > > > related to program execution into memory, but still be able to mmap > > > big file or allocate huge amount of memory and allow OS to swap them on > > > demand. MAP_UNLOCKED allows to do that. > > > > > > Signed-off-by: Gleb Natapov > > > --- > > > > > > I get reports that people find this useful, so resending. > > > > This description is still wrong. It doesn't describe why this patch is useful. > > > I think the text above describes the feature it adds and its use > case quite well. Can you elaborate what is missing in your opinion, > or suggest alternative text please? My point is, introducing mmap new flags need strong and clearly use-case. All patch should have good benefit/cost balance. the code can describe the cost, but the benefit can be only explained by the patch description. I don't think this poor description explained bit benefit rather than cost. you should explain why this patch is useful and not just pretty toy. -- 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