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Mon, 13 Oct 2025 23:43:25 -0700 (PDT) MIME-Version: 1.0 References: <20251014035846.1519-1-21cnbao@gmail.com> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Tue, 14 Oct 2025 14:43:13 +0800 X-Gm-Features: AS18NWBkvzMB1sYbudY7gB27K6cY5x7_rxgh42n5L8scA-jiQSzN7FZuNS0QWLY Message-ID: Subject: Re: [RFC PATCH] mm: net: disable kswapd for high-order network buffer allocation To: Eric Dumazet Cc: corbet@lwn.net, davem@davemloft.net, hannes@cmpxchg.org, horms@kernel.org, jackmanb@google.com, kuba@kernel.org, kuniyu@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linyunsheng@huawei.com, mhocko@suse.com, netdev@vger.kernel.org, pabeni@redhat.com, surenb@google.com, v-songbaohua@oppo.com, vbabka@suse.cz, willemb@google.com, zhouhuacai@oppo.com, ziy@nvidia.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Stat-Signature: 6mo4mbgb65hbdx7uy6y1wehxjuebr5ts X-Rspam-User: X-Rspamd-Queue-Id: BB868C0006 X-HE-Tag: 1760424206-599893 X-HE-Meta: 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 AGpowETL qgkh3iH0g1N3sMEs= 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: > > > > A problem with the existing sysctl is that it only covers the TX path; > > for the RX path, we also observe that kswapd consumes significant power. > > I could add the patch below to make it support the RX path, but it feels > > like a bit of a layer violation, since the RX path code resides in mm > > and is intended to serve generic users rather than networking, even > > though the current callers are primarily network-related. > > You might have a buggy driver. We are observing the RX path as follows: do_softirq taskset_hi_action kalPacketAlloc __netdev_alloc_skb page_frag_alloc_align __page_frag_cache_refill This appears to be a fairly common stack. So it is a buggy driver? > > High performance drivers use order-0 allocations only. > Do you have an example of high-performance drivers that use only order-0 memory? Thanks Barry