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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBBCEC433FE for ; Fri, 4 Nov 2022 23:23:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 63D1C6B0078; Fri, 4 Nov 2022 19:23:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5C5AF6B007B; Fri, 4 Nov 2022 19:23:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 48DAB8E0001; Fri, 4 Nov 2022 19:23:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 356886B0078 for ; Fri, 4 Nov 2022 19:23:01 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id DD45FAC24C for ; Fri, 4 Nov 2022 23:23:00 +0000 (UTC) X-FDA: 80097337320.19.3529348 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) by imf09.hostedemail.com (Postfix) with ESMTP id 6AFBF140007 for ; Fri, 4 Nov 2022 23:23:00 +0000 (UTC) Received: by mail-pl1-f176.google.com with SMTP id io19so6216014plb.8 for ; Fri, 04 Nov 2022 16:23:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=EtYEsODmOJKvYgJZvGMTSL9jwi2RIaTO198SEqeZWk8=; b=Yx+CBKf4b3KimfG4I1K3wtyMnr4zWBmG9vP+RGZKvxAKi2aXG9ZT3RSjIEEkARv+y4 2yq+bckIcAk9EMJtiAgzpW39dwVAQODD4yMMEI0ZVIYlrvffXa9VtmUTJ6OugBkAHOww AreU5v+ERdUcXBB7IhPjpSsMbF0Km0Wyaz3eo= 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:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=EtYEsODmOJKvYgJZvGMTSL9jwi2RIaTO198SEqeZWk8=; b=ELzsk1cf3XSEWEiW+DUtGdeTqcLYBQIexn/5r3/jjQDoNuXbU8V/FaBBryqVQev8zV JVoTP+7jS20gEVhrkHr8kG8AcBoLKWjlwVOIYWSe2QmrSQrTdESzMFK41v+Temq+GD9a Xwf6+koi2gfz1TBNeVCs+2wZmczJhylxExTxeIUoT+I0RZsQw0ewcn6EfNAY6LrfXuVp B3dMdemiluZq9vyRTKAtcyECxmze8MCDduRETm3HqxlOHw/WWqYNpEvkKXvyWJVhg4TV B3a7OyAnyRXs4bA5e/oNr1X64oKld+Vsl17OpCROPQzlyVdGqM/JJ+yHA0WO0UnFbAjy m85g== X-Gm-Message-State: ACrzQf08EFhIPL37WtyodCYpUHoHTzuerLVQmOP23cXn6ZCuIvoy9D8y nao4qu5VEOZlvTEX7sS62s0Dlg== X-Google-Smtp-Source: AMsMyM5GU5/IpL3gkA0TW2Vgms2y3dZj/AWxzTNpIvA/UlCRAFs0WcnyIDOnjHUFGluK+YQcmeQC2Q== X-Received: by 2002:a17:902:b581:b0:186:fb90:1151 with SMTP id a1-20020a170902b58100b00186fb901151mr37666494pls.43.1667604179246; Fri, 04 Nov 2022 16:22:59 -0700 (PDT) Received: from google.com ([240f:75:7537:3187:f2f6:8f5:87c8:3aeb]) by smtp.gmail.com with ESMTPSA id m20-20020a635814000000b0046ff7db0984sm234228pgb.72.2022.11.04.16.22.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Nov 2022 16:22:58 -0700 (PDT) Date: Sat, 5 Nov 2022 08:22:54 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Andrew Morton , Nitin Gupta , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv4 4/9] zram: Introduce recompress sysfs knob Message-ID: References: <20221018045533.2396670-1-senozhatsky@chromium.org> <20221018045533.2396670-5-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=Yx+CBKf4; spf=pass (imf09.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.214.176 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667604180; a=rsa-sha256; cv=none; b=37rZ+VhKiiT/D+TxEhPfZiDuxvYgL1CoQoTWuFFf7SRCShwdpPWw+rgLeGWbFy5YcPqM9H G/k4FLBSBRhonIxYfp/p/A2quLRMnlt/OtQukpFLnFEx75vfsqEtiYaxfymn0Rq4UaBZXK T29Y4Cq7D505ZGJ8CR/zJJWUcORhqi4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667604180; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=EtYEsODmOJKvYgJZvGMTSL9jwi2RIaTO198SEqeZWk8=; b=3OuNQBB4QxmamZReyTZxIyltN7ue193Fc6Yqkef5cZstJNWdBo9miynnxsXyww1onKr0yb RQ5DPujabjS1H52ApRf5W3hPldU36SCm5gkESGeVaBvuV+iXuDi6bfV4cqqfUyRNAnFxME G0t8UqPNRYtAUe5OPxKH/sOxaFnDYrs= X-Stat-Signature: qq9ccwxoessx6tj15wc6jr4u6qkqqx7z X-Rspamd-Queue-Id: 6AFBF140007 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=Yx+CBKf4; spf=pass (imf09.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.214.176 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1667604180-142802 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000025, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On (22/11/04 10:27), Minchan Kim wrote: > > objects that are in-compressible (in a way that saves us memory in > > zsmalloc) by any of the ZRAM's algorithms. > > > > > read_block_state > > > zram_algo_idx(zram, index) > 0 ? 'r' : '.'); > > > > > > zram_read_from_zpool > > > if (zram_algo_idx(zram, idx) != 0) > > > idx = 1; > > > > As an idea, maybe we can store everything re-compression related > > in a dedicated meta field? SKIP flag, algorithm ID, etc. > > > > We don't have too many bits left in ->flags on 32-bit systems. We > > currently probably need at least 3 bits - one for RECOMP_SKIP and at > > least 2 for algorithm ID. 2 bits for algorithm ID put us into situation > > that we can have only 00, 01, 10, 11 as IDs, that is maximum 3 recompress > > algorithms: 00 is the primary one and the rest are alternative ones. > > Maximum 3 re-compression algorithms sounds like a reasonable max value to > > me. Yeah, maybe we can use flags bits for it. > > If possbile, let's go with those three bits into flags since we could > factor them out into dedicated field, anytime later since it's not ABI. Ack.