From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 4 Feb 2004 10:53:15 -0800 From: Andrew Morton Subject: Re: [PATCH 3/5] mm improvements Message-Id: <20040204105315.3644dcd3.akpm@osdl.org> In-Reply-To: <16417.8644.203682.640759@laputa.namesys.com> References: <4020BE45.10007@cyberone.com.au> <16417.8644.203682.640759@laputa.namesys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nikita Danilov Cc: riel@redhat.com, piggin@cyberone.com.au, linux-mm@kvack.org List-ID: Nikita Danilov wrote: > > Rik van Riel writes: > > On Wed, 4 Feb 2004, Nick Piggin wrote: > > > Nick Piggin wrote: > > > > > > > 3/5: vm-lru-info.patch > > > > Keep more referenced info in the active list. Should also improve > > > > system time in some cases. Helps swapping loads significantly. > > > > I suspect this is one of the more important ones in this > > batch of patches... > > I don't understand how this works. This patch just parks mapped pages on > the "ignored" segment of the active list, where they rest until > reclaim_mapped mode is entered. > > This only makes a difference for the pages that were page_referenced(): > > 1. they are moved to the ignored segment rather than to the head of the > active list. > > 2. their referenced bit is not cleared > > Now, as "ignored" segment is not scanned in !reclaim_mode, (2) would > only make a difference when VM rapidly oscillates between reclaim_mapped > and !reclaim_mapped, because after a long period of !reclaim_mapped > operation preserved referenced bit on a page only means "this page has > been referenced in the past, but not necessary recently". Yes, reclaim_mapped shouldn't change at all frequently, unless the zone->prev_priority thing is broken. prev_priority is supposed to remember the reclaim_mapped state between successive scan attempts so we go straight into doing the right thing. It _was_ working - I instrumented and tested that when it went in. It was a bit tricky to get right. -- 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: aart@kvack.org