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Tue, 02 Sep 2025 03:07:11 -0700 (PDT) MIME-Version: 1.0 References: <20250822192023.13477-1-ryncsn@gmail.com> <20250822192023.13477-8-ryncsn@gmail.com> In-Reply-To: <20250822192023.13477-8-ryncsn@gmail.com> From: Barry Song <21cnbao@gmail.com> Date: Tue, 2 Sep 2025 18:06:59 +0800 X-Gm-Features: Ac12FXzr_QuDNQ1ketQVI0L0O2e5pn7ImaHsrDqHTF4iWbuQt0_ufzEsJP1Vm7g Message-ID: Subject: Re: [PATCH 7/9] mm, swap: remove contention workaround for swap cache To: Kairui Song Cc: linux-mm@kvack.org, Andrew Morton , Matthew Wilcox , Hugh Dickins , Chris Li , Baoquan He , Nhat Pham , Kemeng Shi , Baolin Wang , Ying Huang , Johannes Weiner , David Hildenbrand , Yosry Ahmed , Lorenzo Stoakes , Zi Yan , linux-kernel@vger.kernel.org, kernel test robot Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 72C221C0006 X-Stat-Signature: uhd8j1w34aeyto1376e84i9uwrasnreu X-HE-Tag: 1756807632-890057 X-HE-Meta: U2FsdGVkX1+3RQDaxqA35WnFgWwWUFZMQX7NIo4iOeshlkfxW1+X89sIYljfZumLsKQ3kjg3zSl7AkR7pcqNDXzTnMvBhCmV3Zth8ljeynYF2wem2mtryAb67e8+NJLdSWCBRGcqFcFWmhWFbmwdO2OZm3sGq3Ey6P7CIKaoXZBsZtxpgh1aJ4pO2H6k1YMw2enGd7h7N2yDprl8TcE3taCiYa9ZOXSq6vn+tLYhRH5iYOIKfkjFhvt8FPI7zAyznFIe7r77A3GSXAW1HgwlD0CNNiTu2AHZUwyjZyyqG9eRfqCxy89dOTm/fg35NafJErswC+GIhwXsEtA+l/qE8OuJ+yB1Gi6PVG7vMKnhMOQ73e3igVaWkqbx9orcSOskr8jBvy79V+GWozeKf71ikJoVebjaksXWndw2RqTjSaiI7EDcjP0Fh4SIlzfl05KXoQlnNHiFO3L+7avdAgTYF/zcpWGGnAA8vWQhf+a833PpzDZqcxZsTMJlLqWU9UaU8DCNub9utZVUAPiAj5MIX6SFsPYtiEGiE7ZKp4emUkf+Yk/8r8MaRtbg6O3pVyZg8dQwsSWMSiqxOzQB9qEcrvig3COWqkTc+zQGOqiV7ICKb33UeVNY/SmBivhEDfMrGpek5dAYNTxaznUWzc9fQneSVwKkKhGo1Y3mfojsCRPMHHkTlcxWGi8o1ZsMUfNhEt7SKchy6IFsyzxU3IFvdWa2LG95U9Lp3Ebcz/XCzQwbMlvpTno7YT2SVguxemVFWkE6xrHxNj85vjsm5ASz/JJtG5EePTrBegrGa9u/vcHWa4bkmVwybsF8ZhzrVxCBJgAoISZPVlgVRWd9wtMe4ay4XTDGF0FHIo8kr9F43ZFg+qw5mhQ5UKxHkBdAkYuFnHLNpUP7Zv6etOzmM8FzIPve4L1uRkhqXcdKAi7gB64CR2kbX1A4fmnGphahJC5ewjBi6bOkqgHNkoe8a00 0TPbQN4G vjbJPlBkkp4L8nItAhkQdT3CvXgkxkAB1+yu+Cxvb7WVvRRI/znu5/W/fgjp2arxlRvqqwm1wtPdnhbnAcN0J9WkKpL+yN0r5snb2WrP0R6eDChPFrMobw+t9YHPvoC98R5r0Df9Zb2tlGmCY4yfCgyolW75J3FoYrkZwXmcBDnc8LIUVThppEx00U9hQ6SM+9H7emAO7CCcKTpgj5nd8C7tCtnC2S+Xz4qIajFAvt5iII2EHfMwXUSzly0CQe2n1xhL5gLW2ShC1aRsSjNowT/So31RLKBXSfPLfFeUA+HxXuWs9AOaC14LQ8kOS/hKkJu3sqhHENdZ6oGd4W14Jn9XhH24Ze18thdANqnlkjmN2iN/S+bg3IpFOVVxTvv+Kd04mjZZifQacPwhztmUcgiEmGtyyjoMsfus0+bAvWnfg/k5ZXCVpdhG/sAUXhsC9YIIg 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 Sat, Aug 23, 2025 at 3:21=E2=80=AFAM Kairui Song wrot= e: > > From: Kairui Song > > Swap cluster setup will try to shuffle the clusters on initialization. > It was helpful to avoid contention for the swap cache space. The cluster > size (2M) was much smaller than each swap cache space (64M), so shuffling > the cluster means the allocator will try to allocate swap slots that are > in different swap cache spaces for each CPU, reducing the chance of two > CPUs using the same swap cache space, and hence reducing the contention. > > Now, swap cache is managed by swap clusters, this shuffle is pointless. > Just remove it, and clean up related macros. > > This should also improve the HDD swap performance as shuffling IO is a > bad idea for HDD, and now the shuffling is gone. > > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-lkp/202504241621.f27743ec-lkp@intel.co= m > Signed-off-by: Kairui Song > --- Reviewed-by: Barry Song