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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> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667359744; 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; 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spf=pass (imf30.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.210.178 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Stat-Signature: 3sct1j4uqcxkhhxp9w6njsqnk83zunyu X-HE-Tag: 1667359743-540259 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000270, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.