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Mon, 13 Apr 2026 22:50:45 -0700 (PDT) From: Xueyuan Chen To: ryncsn@gmail.com Cc: baohua@kernel.org, minchan@kernel.org, senozhatsky@chromium.org, akpm@linux-foundation.org, linux-mm@kvack.org, axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, kasong@tencent.com, chrisl@kernel.org, justinjiang@vivo.com, liulei.rjpt@vivo.com, xueyuan.chen21@gmail.com Subject: Re: [RFC PATCH] zram: support asynchronous GC for lazy slot freeing Date: Tue, 14 Apr 2026 13:49:30 +0800 Message-ID: <20260414054930.225853-1-xueyuan.chen21@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: g4u7ogz63tfyx7zmnb4a4o31thmoxbfx X-Rspamd-Queue-Id: 94B64100003 X-Rspamd-Server: rspam09 X-HE-Tag: 1776145848-332395 X-HE-Meta: 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 SX3zRJFK 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Apr 12, 2026 at 07:48:48PM +0800, Kairui Song wrote: [...] >What is making this slot_free so costly? zs_free? Yes, I've captured some perf data on RK3588 cpu2: - 3.79% 0.42% zram [zram] [k] slot_free - 89.04% slot_free - 65.40% zs_free + 77.29% free_zspage + 21.75% kmem_cache_free 0.68% __kern_my_cpu_offset + 13.19% _raw_spin_unlock + 4.86% _raw_read_unlock 4.75% obj_free + 4.72% _raw_read_lock 3.64% fix_fullness_group + 2.02% _raw_spin_lock + 1.31% kmem_cache_free It's clear that zs_free is the primary hotspot, accounting for ~65.40% of the total slot_free cycles. Beyond that, have some read and spin lock in slot_free. -- Thanks, Xueyuan