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AJvYcCWWEIlekwhgDkx0/cvU+xkME7Aza8Huf92pWBJQmoaFrc1eumFInLoNrBG9GSWVDTNAwxZrBR3+eA==@kvack.org X-Gm-Message-State: AOJu0Yzlh3QB+/LTeDxmpsv2MzpmV9lqOeGr8e2l/0A0tVg/eTXz3KiL iP9CQ5clnQk89hbCYwSDzUt1ZVlFZIABtA+0v6wbjb8sLY+DoAynm3+EICfWwXhw6+DXOKyPyZ/ kVVeVEkg52KtQ3AijrVFpDotC9dsUty8= X-Gm-Gg: ASbGncuyrvT58dd0SvHoyBs5cRAWRyT06IUAmz1NEELTVKe1WoCyLs+wC0V9HcsREd0 t5RAIjJS0w8lB3JhDo5LZQkrOpghItH0Gr1MM0j6fiviLxH1gl0H0g0OUFDHEG1Qp56e7bTZ5BW x5j/4yobS5KVesb3R5pd2Xxr4cbUWBkSf+TNk/HfiIys2tBV2r0UIHTYSOo+QEvgE8GuXPEyR3F XEfTiEsBy8+YhwQhP8gjYjK5YlQDTW8Uqx2vPwY8j9C0RFdifE1eiCmsw== X-Google-Smtp-Source: AGHT+IETi+Y5YVwDc4yOoULmeg0a/9GeqOMfyBB7w5srSvCikgvrnPsYVAaDacZCpZa84Vw9/offBLIwQL/Ei3+rCbk= X-Received: by 2002:a05:620a:2696:b0:883:9634:5182 with SMTP id af79cd13be357-883963455a8mr2869615085a.2.1760414970813; Mon, 13 Oct 2025 21:09:30 -0700 (PDT) MIME-Version: 1.0 References: <20251013101636.69220-1-21cnbao@gmail.com> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Tue, 14 Oct 2025 12:09:19 +0800 X-Gm-Features: AS18NWCg3XvdE0hLImKQoNMslsxmyNkYfWghrFBQZL30dkAgd-aSHHY4CyF1lvs Message-ID: Subject: Re: [RFC PATCH] mm: net: disable kswapd for high-order network buffer allocation To: Matthew Wilcox Cc: netdev@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Barry Song , Jonathan Corbet , Eric Dumazet , Kuniyuki Iwashima , Paolo Abeni , Willem de Bruijn , "David S. Miller" , Jakub Kicinski , Simon Horman , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Yunsheng Lin , Huacai Zhou Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 4r86xofdkfndkjajhwhjq3m3jpqcz8jm X-Rspamd-Queue-Id: E5FCE100006 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1760414971-128785 X-HE-Meta: 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 XP/CAisg +UTpH5OGziyFamW4zlJDGNbHNzEJG5sJzMTuc5vxr2SfBJ4y0GDsUKrzvR0kqIp+L6P6SzP9DTXk2PQ419LXSCjm46Tn2WLc3lRhoaCvdCglQVCaKI945+yhHgpi34IaQz6R7H9O5PJySBWpAdpvKyz9W3zmd+QjGi77I6s9KoFfqhLDxdYk5NEGdt2mQxLQ0XkU7iunrgePgWY+Vb5Q2xNoiZNKUDVKX0U5mdWXtzN8XGA2QMM+jSfwoh+8RQAjQplGhGUWhflvlWmwN9hMLX+gLmw4JEjfmwyahXw118D/euHumNmpfXjvHbyp00dR6iMJhKq6pARcdU2cCA//99rvZAOGfFTH7g5jojkDsbxvg+yrFG1LkfONW2dj9SJ68XrntrRZMfi+67yCz/WvjwS2tecVbJPqDFft4 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 Tue, Oct 14, 2025 at 5:56=E2=80=AFAM Matthew Wilcox wrote: > > On Mon, Oct 13, 2025 at 06:16:36PM +0800, Barry Song wrote: > > On phones, we have observed significant phone heating when running apps > > with high network bandwidth. This is caused by the network stack freque= ntly > > waking kswapd for order-3 allocations. As a result, memory reclamation = becomes > > constantly active, even though plenty of memory is still available for = network > > allocations which can fall back to order-0. > > I think we need to understand what's going on here a whole lot more than > this! > > So, we try to do an order-3 allocation. kswapd runs and ... succeeds in > creating order-3 pages? Or fails to? > Our team observed that most of the time we successfully obtain order-3 memory, but the cost is excessive memory reclamation, since we end up over-reclaiming order-0 pages that could have remained in memory. > If it fails, that's something we need to sort out. > > If it succeeds, now we have several order-3 pages, great. But where do > they all go that we need to run kswapd again? The network app keeps running and continues to issue new order-3 allocation requests, so those few order-3 pages won=E2=80=99t be enough to satisfy the continuous demand. Thanks Barry