From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC6ADC433EF for ; Fri, 3 Sep 2021 19:02:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAE3E610A1 for ; Fri, 3 Sep 2021 19:02:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350603AbhICTDW (ORCPT ); Fri, 3 Sep 2021 15:03:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239381AbhICTDU (ORCPT ); Fri, 3 Sep 2021 15:03:20 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F383C061575 for ; Fri, 3 Sep 2021 12:02:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=aH/w/+Cnoi5Txr0//vfK/74qoG/0s9SMxp4KCpOEQNc=; b=Udk67ofuMPuRnJfAeSghwUmZR3 8t2sYr5DhN6waO8X8Bk9jTiLqDqp/m3y25qQbEUaE9ESWhBa3JP3YY/8NyHm0CWcZ8CxHCt64yDyG xwitDvpshWWmP7kquY3hSizYINAjhsTo242vfIpX0aAMtuNWDc1vjOfPf4neM4XVMwSOzEVbcruYO M57mbCbwWmtkwZ1ePynw+AyjNPd0sjBICUmFpvdT1yBkslO54lt/cQpkA37n/54mbLRP/krQdAblY zrsCsdQMYsmkqJwDdvGA6M1Np8lDW5YUR903PZCRYBIbnDgFmg4yjacx4C3MXH929iDE5DNDGsxQy 6gi3G0sA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mMERa-004hkO-HP; Fri, 03 Sep 2021 19:01:49 +0000 Date: Fri, 3 Sep 2021 20:01:42 +0100 From: Matthew Wilcox To: Nicholas Piggin Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Shijie Huang , song.bao.hua@hisilicon.com, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, Frank Wang Subject: Re: Is it possible to implement the per-node page cache for programs/libraries? Message-ID: References: <1630552995.2mupnzoqzs.astroid@bobo.none> <1630652670.aplcvu6g23.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1630652670.aplcvu6g23.astroid@bobo.none> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 03, 2021 at 05:10:31PM +1000, Nicholas Piggin wrote: > Excerpts from Matthew Wilcox's message of September 2, 2021 8:17 pm: > > On Thu, Sep 02, 2021 at 01:25:36PM +1000, Nicholas Piggin wrote: > >> > I have been thinking about this a bit; one of our internal performance > >> > teams flagged the potential performance win to me a few months ago. > >> > I don't have a concrete design for text replication yet; there have been > >> > various attempts over the years, but none were particularly compelling. > >> > >> What was not compelling about it? > > > > It wasn't merged, so clearly it wasn't compelling enough? > > Ha ha. It sounded like you had some reasons you didn't find it > particularly compelling :P I haven't studied it in detail, but it seems to me that your patch (from 2007!) chooses whether to store pages or pcache_desc pointers in i_pages. Was there a reason you chose to do it that way instead of having per-node i_mapping pointers? (And which way would you choose to do it now, given the infrastructure we have now?)