From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 14 Jan 2000 03:13:48 +0100 (CET) From: Ingo Molnar Subject: Re: [RFC] 2.3.39 zone balancing In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Andrea Arcangeli , Kanoj Sarcar , Alan Cox , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.rutgers.edu List-ID: On Thu, 13 Jan 2000, Linus Torvalds wrote: > HOWEVER, I don't think this is going to be a huge issue in most cases. And > if people don't need non-DMA memory, then the pages we "swapped" out are > going to stay in RAM anyway, so it's not going to hurt us. > > Anyway, I obviously do agree that I may well be wrong, and that real life > is going to come back and bite us, and we'll end up having to not do it > this way. However, I'd prefer trying the "conceptually simple" path first, > and only if it turns out that yes, I was completely wrong, do we try to > fix it up with magic heuristics etc. hm., i think we'll see this with ISA soundcards (still the majority) if used as modules. Right now kswapd just gives up too easy and says 'no such page', on a box with lots of RAM and all DMA allocated in process VM space. Anyway, the patch and suggestion of passing in a single zone is i believe completely wrong, because it advances mm->swap_address, which unfairly selects a given range to be checked for only one zone. So i think it's either zone-bitmaps (or equivalent multi-zone logic) or what you suggested, to have no zone-awareness in swap_out() for now at all. (i believe this is also going to bite us with the IA64 port - kswapd will have no information to free pages from the right node, we could solve this already with a zone bitmap, or by starting per-zone kswapds. The latter one looks like overkill to me, but it's conceptually cleaner than bitmaps and and does not have a limitation on the number of zones. Might not be a highprio issue though.) -- mingo -- 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.nl.linux.org/Linux-MM/