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 9D1B6C77B73 for ; Thu, 20 Apr 2023 14:58:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231758AbjDTO62 (ORCPT ); Thu, 20 Apr 2023 10:58:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49068 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231293AbjDTO60 (ORCPT ); Thu, 20 Apr 2023 10:58:26 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D0344C18; Thu, 20 Apr 2023 07:58:17 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 18CD5218E3; Thu, 20 Apr 2023 14:58:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1682002696; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=gDf4XujYppNB9yfIolnvmPiQWugPbK/UQC0PFMlPEMo=; b=P7nvd52LsUKd9ZcwsE9cJ+xvHQ4YwoVQUa81fNln5PZLn/nky/9AyvmKo3lexVYilgS1TR IfjDL1lo+lrSiB1pFH/VCVmgRB0+0BYlGYsbFI0JyO3X6dIn0mSKydcfHo6oyxoYkn6s2S xsmWIrKHAW6ivloDcV8s20nZvvSKIoQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1682002696; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=gDf4XujYppNB9yfIolnvmPiQWugPbK/UQC0PFMlPEMo=; b=/1w8GnyqqkATDhJDhJbLByPmULVmEotyijJ7ZUysGIHOIxs8vvh0JIjMW8AIrdykLdJt09 ns8QoKkQMzO35BDQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 09D4D1333C; Thu, 20 Apr 2023 14:58:16 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id bxVaAghTQWTlSwAAMHmgww (envelope-from ); Thu, 20 Apr 2023 14:58:16 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 9220EA0729; Thu, 20 Apr 2023 16:58:15 +0200 (CEST) Date: Thu, 20 Apr 2023 16:58:15 +0200 From: Jan Kara To: Ojaswin Mujoo Cc: Jan Kara , linux-ext4@vger.kernel.org, Theodore Ts'o , Ritesh Harjani , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Ritesh Harjani Subject: Re: [RFC 04/11] ext4: Convert mballoc cr (criteria) to enum Message-ID: <20230420145815.rs4amtveq4v3qz6p@quack3> References: <9670431b31aa62e83509fa2802aad364910ee52e.1674822311.git.ojaswin@linux.ibm.com> <20230309121122.vzfswandgqqm4yk5@quack3> <20230323105537.rrecw5xqqzmw567d@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu 20-04-23 12:02:44, Ojaswin Mujoo wrote: > On Sat, Mar 25, 2023 at 08:12:36PM +0530, Ojaswin Mujoo wrote: > > On Thu, Mar 23, 2023 at 11:55:37AM +0100, Jan Kara wrote: > > > On Fri 17-03-23 15:56:46, Ojaswin Mujoo wrote: > > > > On Thu, Mar 09, 2023 at 01:11:22PM +0100, Jan Kara wrote: > > > > > Also when going for symbolic allocator scan names maybe we could actually > > > > > make names sensible instead of CR[0-4]? Perhaps like CR_ORDER2_ALIGNED, > > > > > CR_BEST_LENGHT_FAST, CR_BEST_LENGTH_ALL, CR_ANY_FREE. And probably we could > > > > > deal with ordered comparisons like in: > > > > I like this idea, it should make the code a bit more easier to > > > > understand. However just wondering if I should do it as a part of this > > > > series or a separate patch since we'll be touching code all around and > > > > I don't want to confuse people with the noise :) > > > > > > I guess a mechanical rename should not be really confusing. It just has to > > > be a separate patch. > > Alright, got it. > > > > > > > > > > > > > if (cr < 2 && > > > > > (!sbi->s_log_groups_per_flex || > > > > > ((group & ((1 << sbi->s_log_groups_per_flex) - 1)) != 0)) & > > > > > !(ext4_has_group_desc_csum(sb) && > > > > > (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))) > > > > > return 0; > > > > > > > > > > to declare CR_FAST_SCAN = 2, or something like that. What do you think? > > > > About this, wont it be better to just use something like > > > > > > > > cr < CR_BEST_LENGTH_ALL > > > > > > > > instead of defining a new CR_FAST_SCAN = 2. > > > > > > Yeah, that works as well. > > > > > > > The only concern is that if we add a new "fast" CR (say between > > > > CR_BEST_LENGTH_FAST and CR_BEST_LENGTH_ALL) then we'll need to make > > > > sure we also update CR_FAST_SCAN to 3 which is easy to miss. > > > > > > Well, you have that problem with any naming scheme (and even with numbers). > > > So as long as names are all defined together, there's reasonable chance > > > you'll remember to verify the limits still hold :) > > haha that's true. Anyways, I'll try a few things and see what looks > > good. Thanks for the suggestions. > Hey Jan, > > So I was playing around with this and I prepare a patch to convert CR > numbers to symbolic names and it looks good as far as things like these > are concerned: > > if (cr < CR_POWER2_ALIGNED) > ... > > However there's one problem that this numeric naming scheme is used in > several places like struct member names, function names, traces and > comments. The issue is that replacing it everywhere is making some of > the names very long for example: > > atomic_read(&sbi->s_bal_cr0_bad_suggestions)); > > becomes: > > atomic_read(&sbi->s_bal_cr_power2_aligned_bad_suggestions)); > > And this is kind of making the code look messy at a lot of places. So > right now there are a few options we can consider: > > 1. Use symbolic names everywhere at the cost of readability Can we maybe go with 1b) being: Use symbolic names in variables / members / ... but shortened? Like s_bal_p2aligned_bad_suggestions? Not sure how many things are like this but from a quick looks it seems we need to come up with a sensible shortcut only for cr0 and cr1? Honza -- Jan Kara SUSE Labs, CR