From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx149.postini.com [74.125.245.149]) by kanga.kvack.org (Postfix) with SMTP id 9247A6B004D for ; Sun, 1 Jan 2012 02:18:25 -0500 (EST) Received: by iacb35 with SMTP id b35so33309168iac.14 for ; Sat, 31 Dec 2011 23:18:24 -0800 (PST) Date: Sat, 31 Dec 2011 23:18:15 -0800 (PST) From: Hugh Dickins Subject: Re: [PATCH 3/3] mm: take pagevecs off reclaim stack In-Reply-To: <20111229195917.13f15974.akpm@linux-foundation.org> Message-ID: References: <20111229145548.e34cb2f3.akpm@linux-foundation.org> <4EFD04B2.7050407@gmail.com> <20111229195917.13f15974.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: KOSAKI Motohiro , Konstantin Khlebnikov , linux-mm@kvack.org, Mel Gorman On Thu, 29 Dec 2011, Andrew Morton wrote: > > This is not all some handwavy theoretical thing either. If we've gone > and introduced serious latency issues, people *will* hit them and treat > it as a regression. Sure, though the worst I've seen so far (probably haven't been trying hard enough yet, I need to go for THPs) is 39 pages freed in one call. Regression? Well, any bad latency would already have been there on the gathering side. > > Now, a way out here is to remove lumpy reclaim (please). And make the > problem not come back by promising to never call putback_lru_pages(lots > of pages) (how do we do this?). We can very easily put a counter in it, doing a spin_unlock_irq every time we hit the max. Nothing prevents that, it's just an excrescence I'd have preferred to omit and have not today implemented. > > So I think the best way ahead here is to distribute this patch in the > same release in which we remove lumpy reclaim (pokes Mel). I'm sure there are better reasons for removing lumpy than that I posted a patch which happened to remove some limitation. No need to poke Mel on my behalf! 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org