From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: Re: [PATCH][RFC] add MAP_UNLOCKED mmap flag Date: Tue, 6 Oct 2009 19:27:56 +0900 (JST) Message-ID: <20091006192454.1272.A69D9226@jp.fujitsu.com> References: <20091006190938.126F.A69D9226@jp.fujitsu.com> <20091006102136.GH9832@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20091006102136.GH9832@redhat.com> 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 List-Id: linux-api@vger.kernel.org > On Tue, Oct 06, 2009 at 07:11:06PM +0900, KOSAKI Motohiro wrote: > > Hi > > > > > 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. 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 > > > > Why don't you use explicit munlock()? > Because mmap will fail before I'll have a chance to run munlock on it. > Actually when I run my process inside memory limited container host dies > (I suppose trashing, but haven't checked). > > > Plus, Can you please elabrate which workload nedd this feature? > > > I wanted to run kvm with qemu process locked in memory, but guest memory > unlocked. And guest memory is bigger then host memory in the case I am > testing. I found out that it is impossible currently. 1. process creation (qemu) 2. load all library 3. mlockall(MCL_CURRENT) 4. load guest OS is impossible? why? -- 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