From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f52.google.com (mail-wm0-f52.google.com [74.125.82.52]) by kanga.kvack.org (Postfix) with ESMTP id AF8606B0005 for ; Fri, 19 Feb 2016 17:19:52 -0500 (EST) Received: by mail-wm0-f52.google.com with SMTP id c200so95715907wme.0 for ; Fri, 19 Feb 2016 14:19:52 -0800 (PST) Received: from mail.anarazel.de (mail.anarazel.de. [217.115.131.40]) by mx.google.com with ESMTP id c21si15605550wmd.111.2016.02.19.14.19.51 for ; Fri, 19 Feb 2016 14:19:51 -0800 (PST) Date: Fri, 19 Feb 2016 14:19:39 -0800 From: Andres Freund Subject: Re: Unhelpful caching decisions, possibly related to active/inactive sizing Message-ID: <20160219221939.ywgfdeeaitlgnw44@alap3.anarazel.de> References: <20160209165240.th5bx4adkyewnrf3@alap3.anarazel.de> <20160209224256.GA29872@cmpxchg.org> <20160211153404.42055b27@cuia.usersys.redhat.com> <20160212124653.35zwmy3p2pat5trv@alap3.anarazel.de> <20160212193553.6pugckvamgtk4x5q@alap3.anarazel.de> <20160217161744.6ce0b1e5@annuminas.surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160217161744.6ce0b1e5@annuminas.surriel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka On 2016-02-17 16:17:44 -0500, Rik van Riel wrote: > On Fri, 12 Feb 2016 20:35:53 +0100 > Andres Freund wrote: > > > On 2016-02-12 13:46:53 +0100, Andres Freund wrote: > > > I'm wondering why pages that are repeatedly written to, in units above > > > the page size, are promoted to the active list? I mean if there never > > > are any reads or re-dirtying an already-dirty page, what's the benefit > > > of moving that page onto the active list? > > > > We chatted about this on IRC and you proposed testing this by removing > > FGP_ACCESSED in grab_cache_page_write_begin. I ran tests with that, > > after removing the aforementioned code to issue posix_fadvise(DONTNEED) > > in postgres. > > That looks promising. Indeed. > > Here the active/inactive lists didn't change as much as I hoped. A bit > > of reading made it apparent that the workingset logic in > > add_to_page_cache_lru() defated that attempt, > > The patch below should help with that. > > Does the GFP_ACCESSED change still help with the patch > below applied? I've not yet run any tests, but I'd earlier used perf probes to see where pages got activated, and I saw activations from both places. So presumably there'd be a difference; i.e. ISTM we need to change both places. Regards, Andres -- 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