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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: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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