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Mon, 22 Jan 2024 23:46:30 -0800 (PST) Received: from [10.254.236.83] ([139.177.225.255]) by smtp.gmail.com with ESMTPSA id h20-20020a62b414000000b006d9a9727a8esm11199033pfn.178.2024.01.22.23.46.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 22 Jan 2024 23:46:29 -0800 (PST) Message-ID: <572bfa89-83c3-45ed-abc6-d71b9519813c@bytedance.com> Date: Tue, 23 Jan 2024 15:46:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] mm/zswap: split zswap rb-tree Content-Language: en-US To: Yosry Ahmed Cc: Andrew Morton , Nhat Pham , Chris Li , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Johannes Weiner References: <20240117-b4-zswap-lock-optimize-v2-0-b5cc55479090@bytedance.com> <20240117-b4-zswap-lock-optimize-v2-2-b5cc55479090@bytedance.com> From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 3C34740003 X-Stat-Signature: fq7q56pjqtm8ao6wz6zt5qkmfe6tgzax X-HE-Tag: 1705995991-672821 X-HE-Meta: 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 pj/x9jWa 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/1/23 03:49, Yosry Ahmed wrote: > On Fri, Jan 19, 2024 at 3:22 AM Chengming Zhou > wrote: >> >> Each swapfile has one rb-tree to search the mapping of swp_entry_t to >> zswap_entry, that use a spinlock to protect, which can cause heavy lock >> contention if multiple tasks zswap_store/load concurrently. >> >> Optimize the scalability problem by splitting the zswap rb-tree into >> multiple rb-trees, each corresponds to SWAP_ADDRESS_SPACE_PAGES (64M), >> just like we did in the swap cache address_space splitting. >> >> Although this method can't solve the spinlock contention completely, it >> can mitigate much of that contention. Below is the results of kernel build >> in tmpfs with zswap shrinker enabled: >> >> linux-next zswap-lock-optimize >> real 1m9.181s 1m3.820s >> user 17m44.036s 17m40.100s >> sys 7m37.297s 4m54.622s >> >> So there are clearly improvements. > > If/when you respin this, can you mention that testing was done with a > single swapfile? I assume the improvements will be less with multiple > swapfiles as lock contention should be better. > Ok. Not sure how much improvement, may do some tests later. >> >> Acked-by: Johannes Weiner >> Acked-by: Nhat Pham > > I think the diff in zswap_swapoff() should be much simpler with the > tree(s) cleanup removed. Otherwise LGTM. > > Acked-by: Yosry Ahmed Right, thanks!