From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id D720E6B0069 for ; Wed, 23 Nov 2016 00:26:20 -0500 (EST) Received: by mail-pg0-f71.google.com with SMTP id g186so6997629pgc.2 for ; Tue, 22 Nov 2016 21:26:20 -0800 (PST) Received: from mail-pg0-x22d.google.com (mail-pg0-x22d.google.com. [2607:f8b0:400e:c05::22d]) by mx.google.com with ESMTPS id u189si28121493pfu.124.2016.11.22.21.26.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 22 Nov 2016 21:26:20 -0800 (PST) Received: by mail-pg0-x22d.google.com with SMTP id p66so1755570pga.2 for ; Tue, 22 Nov 2016 21:26:20 -0800 (PST) Date: Tue, 22 Nov 2016 21:26:11 -0800 (PST) From: Hugh Dickins Subject: Re: [Intel-gfx] [PATCH 2/2] drm/i915: Make GPU pages movable In-Reply-To: Message-ID: References: <1478271776-1194-1-git-send-email-akash.goel@intel.com> <1478271776-1194-2-git-send-email-akash.goel@intel.com> <20161109112835.kivhola7ux3lw4s6@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Auld Cc: Hugh Dickins , Daniel Vetter , Intel Graphics Development , Sourab Gupta , linux-mm@kvack.org, akash.goel@intel.com On Tue, 22 Nov 2016, Matthew Auld wrote: > On 9 November 2016 at 18:36, Hugh Dickins wrote: > > On Wed, 9 Nov 2016, Daniel Vetter wrote: > >> > >> Hi all -mm folks! > >> > >> Any feedback on these two? It's kinda an intermediate step towards a > >> full-blown gemfs, and I think useful for that. Or do we need to go > >> directly to our own backing storage thing? Aside from ack/nack from -mm I > >> think this is ready for merging. > > > > I'm currently considering them at last: will report back later. > > > > Full-blown gemfs does not come in here, of course; but let me > > fire a warning shot since you mention it: if it's going to use swap, > > then we shall probably have to nak it in favour of continuing to use > > infrastructure from mm/shmem.c. I very much understand why you would > > love to avoid that dependence, but I doubt it can be safely bypassed. > > Could you please elaborate on what specifically you don't like about > gemfs implementing swap, just to make sure I'm following? If we're talking about swap as implemented in mm/swapfile.c, and managed for tmpfs mainly through shmem_getpage_gfp(): that's slippery stuff, private to mm, and I would not want such trickiness duplicated somewhere down in drivers/gpu/drm, where mm developers and drm developers will keep on forgetting to keep it working correctly. But you write of gemfs "implementing" swap (and I see Daniel wrote of "our own backing storage"): perhaps you intend a disk or slow-mem file of your own, dedicated to paging gemfs objects according to your own rules, poked from memory reclaim via a shrinker. I certainly don't have the same quick objection to that: it may be a good way forward, though I'm not at all sure (and would prefer a name distinct from swap, so we wouldn't get confused - maybe gemswap). Hugh -- 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