From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 14 Jan 2000 03:46:55 +0100 (CET) From: Ingo Molnar Subject: Re: [RFC] 2.3.39 zone balancing In-Reply-To: <200001140113.RAA62584@google.engr.sgi.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Kanoj Sarcar Cc: Andrea Arcangeli , Linus Torvalds , Alan Cox , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.rutgers.edu List-ID: On Thu, 13 Jan 2000, Kanoj Sarcar wrote: > But as Linus points out, recovering from that is not that costly > (the page will be in the swapcache mostly, its just the cost of > the page fault). note that i was not worried a bit about swapping performance. Swapping is slow, conceptually. I'm worried about the current pte_young() logic and the fact that pages can evade swap_out() completely just by being used (read access) at least once per scan. This not only makes the system slow (which we dont care), but also unusable in certain cases. This is an existing problem, Alan got 2.2 reports of frequent GFP_DMA failures on 1GB boxes. (weird combination of hardware i agree) The zone rewrite already made the situation much better by ordering zones, and i'll be completely happy if we make the pte_young() branch in try_to_swap_out() at least conditional on memory pressure :-) -- 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/