From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <48DBB0B3.2010500@tungstengraphics.com> Date: Thu, 25 Sep 2008 17:39:31 +0200 From: =?UTF-8?B?VGhvbWFzIEhlbGxzdHLDtm0=?= MIME-Version: 1.0 Subject: Re: [patch] mm: pageable memory allocator (for DRM-GEM?) References: <20080923091017.GB29718@wotan.suse.de> <48D8C326.80909@tungstengraphics.com> <20080925001856.GB23494@wotan.suse.de> <48DB3B88.7080609@tungstengraphics.com> <1222353487.4343.205.camel@koto.keithp.com> In-Reply-To: <1222353487.4343.205.camel@koto.keithp.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8BIT Sender: owner-linux-mm@kvack.org Return-Path: To: Keith Packard Cc: Nick Piggin , "eric@anholt.net" , "hugh@veritas.com" , "hch@infradead.org" , "airlied@linux.ie" , "jbarnes@virtuousgeek.org" , "dri-devel@lists.sourceforge.net" , Linux Memory Management List , Linux Kernel Mailing List List-ID: Keith Packard wrote: > On Thu, 2008-09-25 at 00:19 -0700, Thomas HellstrA?m wrote: > >> If data is >> dirtied in VRAM or the page(s) got discarded >> we need new pages and to set up a copy operation. >> > > Note that this can occur as a result of a suspend-to-memory transition > at which point *all* of the objects in VRAM will need to be preserved in > main memory, and so the pages aren't really 'freed', they just don't > need to have valid contents, but the system should be aware that the > space may be needed at some point in the future. > > Actually, I think the pages must be allowed to be freed, and that we don't put a requirement on "pageable" to keep swap-space slots for these pages. If we hit an OOM-condition during suspend-to-memory that's bad, but let's say we required "pageable" to keep swap space slots for us, the result would perhaps be that another device wasn't able to suspend, or a user-space program was killed due to lack of swap-space prior to suspend. I'm not really sure what's the worst situation, but my feeling is that we should not require swap-space to be reserved for VRAM, and abort the suspend operation if we hit OOM. That would, in the worst case, mean that people with non-UMA laptops and a too small swap partition would see their battery run out much quicker than they expected... /Thomas -- 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