Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758722AbZGHXQo (ORCPT ); Wed, 8 Jul 2009 19:16:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757758AbZGHXQ1 (ORCPT ); Wed, 8 Jul 2009 19:16:27 -0400 Received: from hera.kernel.org ([140.211.167.34]:57764 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758204AbZGHXQ0 (ORCPT ); Wed, 8 Jul 2009 19:16:26 -0400 Message-ID: <4A55286A.6040202@kernel.org> Date: Thu, 09 Jul 2009 08:14:50 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Miklos Szeredi CC: linux-kernel@vger.kernel.org, fuse-devel@lists.sourceforge.net, akpm@linux-foundation.org, npiggin@suse.de Subject: Re: [PATCH 4/4] FUSE: implement direct mmap References: <1245317073-24000-1-git-send-email-tj@kernel.org> <1245317073-24000-5-git-send-email-tj@kernel.org> <4A48EEDC.807@kernel.org> <4A4F3998.5020805@kernel.org> In-Reply-To: X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 08 Jul 2009 23:14:54 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1320 Lines: 35 Hello, Miklos. Miklos Szeredi wrote: > On Sat, 04 Jul 2009, Tejun Heo wrote: >>> Afaics sound drivers now map the dma memory with remap_pfn_range(). >>> Similary we could allocate a chunk of non-swapabble kernel memory on >>> request from the userspace server and map its pages using this trick >>> to both the server's and the client's address space. >>> >>> This is still sort of OSSP specific, I don't see clearly how it could >>> be made more generic. >> Using non-swappable memory would be fine for most device emulations >> but mapping large amount of pages would be problematic. Hmmm... this >> is difficult. It's a compromise among flexibility, scalability and >> code complexity. > > What's the difficulty? The desire to avoid pinning all the mapped pages. :-) > Allocating pages, giving them an ID and mapping them into various page > tables seems simple in contrast to trying to make a tmpfs file be a > fuse file at the same time, which the VM is really not prepared for. If pinning all the pages are okay, the above should work fine. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/