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[34.86.5.128]) by smtp.gmail.com with UTF8SMTPSA id a1e0cc1a2514c-890277bf746sm681112241.5.2025.08.16.02.34.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 16 Aug 2025 02:34:43 -0700 (PDT) Date: Sat, 16 Aug 2025 05:34:43 -0400 From: Willem de Bruijn To: Xin Zhao , willemdebruijn.kernel@gmail.com, edumazet@google.com, ferenc@fejes.dev Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Xin Zhao Message-ID: In-Reply-To: <20250816024831.1451167-1-jackzxcui1989@163.com> References: <20250816024831.1451167-1-jackzxcui1989@163.com> Subject: Re: [PATCH net-next v3] net: af_packet: Use hrtimer to do the retire operation Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Xin Zhao wrote: > In a system with high real-time requirements, the timeout mechanism of > ordinary timers with jiffies granularity is insufficient to meet the > demands for real-time performance. Meanwhile, the optimization of CPU > usage with af_packet is quite significant. Use hrtimer instead of timer > to help compensate for the shortcomings in real-time performance. > In HZ=100 or HZ=250 system, the update of TP_STATUS_USER is not real-time > enough, with fluctuations reaching over 8ms (on a system with HZ=250). > This is unacceptable in some high real-time systems that require timely > processing of network packets. By replacing it with hrtimer, if a timeout > of 2ms is set, the update of TP_STATUS_USER can be stabilized to within > 3 ms. > > Signed-off-by: Xin Zhao Discussion in v2 is still ongoing. This will have to be respun based on that.