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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9C92C54EBD for ; Fri, 13 Jan 2023 17:45:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229581AbjAMRp0 (ORCPT ); Fri, 13 Jan 2023 12:45:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229893AbjAMRos (ORCPT ); Fri, 13 Jan 2023 12:44:48 -0500 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1378576214 for ; Fri, 13 Jan 2023 09:32:24 -0800 (PST) Received: by mail-pj1-x1036.google.com with SMTP id dw9so21661635pjb.5 for ; Fri, 13 Jan 2023 09:32:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=PmYXy2OEtQ8VHSUKHtw2ymRz/ihI4R4a9w+pBYXSPOk=; b=hLV1A+louwagu6kcroNKyxrNallo6byaj7ZHPnU0W+/GRK0nax01Q90awWU6d+vv43 ULDGVYWByxYf9MJq1f+DY1UEnnqLw9XTXJ75m2YYsF3fQSxqVouFC0WdWAXZ/hmvEDZi vpztpxGwNuCC3h+0tg3vKgTGsGTylRY2gEkAv/8xQ+Y9JJqMrH3BGDYBW1vjlZlDck5l q1lu2kWpAe7dL3MvNYj8XMaIyHhcBujnQ/Cir7An0foAFgOFvNMQuScNru543rofLbqx fFz5+WrkewTQZNiRMsLq9esZwORC0bRoxRDlzniRkVJyrPYANWEgF8zbecUAsW7Y6CTs DxUA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=PmYXy2OEtQ8VHSUKHtw2ymRz/ihI4R4a9w+pBYXSPOk=; b=OLCYXVSLVzSoEyainv86uWsawO0+lSE0LLg5qPPVgfEvV9WiHakcDNGBeNTBqqqWOt EsBR1Vmkn3SC+3gnPoK28Nf1T/mzI16BPVLU4+6nKRObSRaMxwXXkcim+F7JeKWgAQOO Ej9/1K4paUq2hk1usqTn5HbHi8QV20SPm4s35giwk3htvelsAmyEjGWJk1yF2UoC48Ma wgTW3dNWaOMexk9IDyuTtfw/rPvLewN7Hsgmo6sIDhHcND5R6WXpzEqlhqS4FUHsa13J ZQRbmVyfyanHcbKZSbzNQPYwlhIARdnbvbZWibIa7LJHkqxEo7BZL7VLKywgTNTvlhHl 6eQQ== X-Gm-Message-State: AFqh2koz3kQRlT61UgsNnjA4KiYMJPEZMZNRTslRjkDt0EkkKJqk+hFk xV1l9wT2oPP7u/5ZLQKkl0g= X-Google-Smtp-Source: AMrXdXuZyYlG0xrvFopsJeYUWHJNpEbJJ7r7UFeIZlj2zJ+CVQQDjGr6jRS9fO898GVGsAyBjT2XCA== X-Received: by 2002:a17:902:bb86:b0:192:afb0:8960 with SMTP id m6-20020a170902bb8600b00192afb08960mr46334594pls.3.1673631143514; Fri, 13 Jan 2023 09:32:23 -0800 (PST) Received: from google.com ([2620:15c:211:201:2e4e:fba:501b:3a8c]) by smtp.gmail.com with ESMTPSA id l6-20020a170903244600b0019467381dd6sm2392322pls.33.2023.01.13.09.32.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Jan 2023 09:32:22 -0800 (PST) Sender: Minchan Kim Date: Fri, 13 Jan 2023 09:32:21 -0800 From: Minchan Kim To: Sergey Senozhatsky Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv2 1/4] zsmalloc: rework zspage chain size selection Message-ID: References: <20230109033838.2779902-1-senozhatsky@chromium.org> <20230109033838.2779902-2-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230109033838.2779902-2-senozhatsky@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 09, 2023 at 12:38:35PM +0900, Sergey Senozhatsky wrote: > Computers are bad at division. We currently decide the best > zspage chain size (max number of physical pages per-zspage) > by looking at a `used percentage` value. This is not enough > as we lose precision during usage percentage calculations > For example, let's look at size class 208: > > pages per zspage wasted bytes used% > 1 144 96 > 2 80 99 > 3 16 99 > 4 160 99 > > Current algorithm will select 2 page per zspage configuration, > as it's the first one to reach 99%. However, 3 pages per zspage > waste less memory. > > Change algorithm and select zspage configuration that has > lowest wasted value. > > Signed-off-by: Sergey Senozhatsky Acked-by: Minchan Kim