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 689FEC433FE for ; Wed, 2 Nov 2022 03:29:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231265AbiKBD3e (ORCPT ); Tue, 1 Nov 2022 23:29:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231238AbiKBD3F (ORCPT ); Tue, 1 Nov 2022 23:29:05 -0400 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A4166410 for ; Tue, 1 Nov 2022 20:29:03 -0700 (PDT) Received: by mail-pf1-x433.google.com with SMTP id m6so15304735pfb.0 for ; Tue, 01 Nov 2022 20:29:03 -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=wxscppbd7CO4HZ9j9/10aVKDgnbCZgFQSCEpVRfHl0Y=; b=cyeIXizddRI28+BjmVZ/J7XNFddHenjeoTfy9K+DT7y0+xtEC7Jll84U9fbRz5QhCP T6cPKGowQzp+hdMXkJzOsylrt0aAoNLfYE6MsG1BrNCdGJGawcf1nVbzTn4cK/sGoP3U 8D4KTAWMm6I+libcyOwmS2112+JqVyRDLdY28= 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=wxscppbd7CO4HZ9j9/10aVKDgnbCZgFQSCEpVRfHl0Y=; b=gOZ4lZh7daagiU+eCabxjZbf1XYLoy1xt7X9nsk16kJAF2FLGDSQnqCJicmFypU2q/ 6qCzWXmPoh2ANMTfYAOSFIPVTLaioCzUHsLmxBZSep5AmvfA5mAflt7pgAbASR9I2Jvj ZHPaBAunWc+wbXO3O8YQKDXpTcYsKzNr4aF6jkjuGB2b4GgvGihh8GbZeGbt+FPmsV3t E3JTE2Tt+DOF5Z0lldCjuMerSyRcZpSkTM+fiBCfylfFyeiN31dcoRh5LC7FcwxjxK1+ Rc6o9XJdkzKCWljnqw56vPdnNfqovA+4GZHg4T5m1RUZN56T9b9LDSkfL0bIIhryC8yY kumg== X-Gm-Message-State: ACrzQf1Zqx/oAufdLO2+vnu2QfJ0RT78W/ZwvmObZcPBS3imYeKJgFHh GP4grvqJehmYsl/tiRNuN0hu4g== X-Google-Smtp-Source: AMsMyM7XbsY6sJWV2ZedoRxQsL0dArAlDm4EY8V7+KE2FaG2i1FNEtHiEcMWQJ6OEd6huZ8OdW6ziA== X-Received: by 2002:a65:4d07:0:b0:46f:ed91:a50d with SMTP id i7-20020a654d07000000b0046fed91a50dmr5308740pgt.343.1667359742885; Tue, 01 Nov 2022 20:29:02 -0700 (PDT) Received: from google.com ([240f:75:7537:3187:f558:dfb0:7cb7:44d9]) by smtp.gmail.com with ESMTPSA id s5-20020a17090a760500b0021282014066sm302684pjk.9.2022.11.01.20.28.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Nov 2022 20:29:02 -0700 (PDT) Date: Wed, 2 Nov 2022 12:28:56 +0900 From: Sergey Senozhatsky To: Nhat Pham Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, minchan@kernel.org, ngupta@vflare.org, senozhatsky@chromium.org, sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com Subject: Re: [PATCH 2/5] zsmalloc: Consolidate zs_pool's migrate_lock and size_class's locks Message-ID: References: <20221026200613.1031261-1-nphamcs@gmail.com> <20221026200613.1031261-3-nphamcs@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221026200613.1031261-3-nphamcs@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (22/10/26 13:06), Nhat Pham wrote: > struct size_class { > - spinlock_t lock; > struct list_head fullness_list[NR_ZS_FULLNESS]; > /* > * Size of objects stored in this class. Must be multiple > @@ -247,8 +245,7 @@ struct zs_pool { > #ifdef CONFIG_COMPACTION > struct work_struct free_work; > #endif > - /* protect page/zspage migration */ > - rwlock_t migrate_lock; > + spinlock_t lock; > }; I'm not in love with this, to be honest. One big pool lock instead of 255 per-class locks doesn't look attractive, as one big pool lock is going to be hammered quite a lot when zram is used, e.g. as a regular block device with a file system and is under heavy parallel writes/reads.