From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: Re: [PATCH v5] add MAP_UNLOCKED mmap flag Date: Thu, 14 Jan 2010 17:17:36 +0900 (JST) Message-ID: <20100114170247.6747.A69D9226@jp.fujitsu.com> References: <20100114162327.673E.A69D9226@jp.fujitsu.com> <20100114080117.GL18808@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100114080117.GL18808-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Gleb Natapov Cc: kosaki.motohiro-+CUm20s59erQFUHtdCDX3A@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org List-Id: linux-api@vger.kernel.org > > Hmm.. > > Your answer didn't match I wanted. > Then I don't get what you want. I want to know the benefit of the patch for patch reviewing. > > few additional questions. > > > > - Why don't you change your application? It seems natural way than kernel change. > There is no way to change my application and achieve what I've described > in a multithreaded app. Then, we don't recommend to use mlockall(). I don't hope to hear your conclusion, it is not objectivization. I hope to hear why you reached such conclusion. > > - Why do you want your virtual machine have mlockall? AFAIK, current majority > > virtual machine doesn't. > It is absolutely irrelevant for that patch, but just because you ask I > want to measure the cost of swapping out of a guest memory. No. if you stop to use mlockall, the issue is vanished. > > - If this feature added, average distro user can get any benefit? > > > ?! Is this some kind of new measure? There are plenty of much more > invasive features that don't bring benefits to an average distro user. > This feature can bring benefit to embedded/RT developers. I mean who get benifit? > > I mean, many application developrs want to add their specific feature > > into kernel. but if we allow it unlimitedly, major syscall become > > the trushbox of pretty toy feature soon. > > > And if application developer wants to extend kernel in a way that it > will be possible to do something that was not possible before why is > this a bad thing? I would agree with you if for my problem was userspace > solution, but there is none. The mmap interface is asymmetric in regards > to mlock currently. There is MAP_LOCKED, but no MAP_UNLOCKED. Why > MAP_LOCKED is useful then? Why? Because this is formal LKML reviewing process. I'm reviewing your patch for YOU. If there is no objective reason, I don't want to continue reviewing.