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Thu, 06 Nov 2025 01:05:15 -0800 (PST) Received: from [192.168.88.32] ([212.105.155.83]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47763da0242sm11361145e9.0.2025.11.06.01.05.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Nov 2025 01:05:14 -0800 (PST) Message-ID: <8ef591e6-9b05-4c7b-8d75-82ced4dd2f31@redhat.com> Date: Thu, 6 Nov 2025 10:05:13 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next] net: add prefetch() in skb_defer_free_flush() To: Eric Dumazet , "David S . Miller" , Jakub Kicinski Cc: Simon Horman , netdev@vger.kernel.org, eric.dumazet@gmail.com References: <20251106085500.2438951-1-edumazet@google.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20251106085500.2438951-1-edumazet@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/6/25 9:55 AM, Eric Dumazet wrote: > skb_defer_free_flush() is becoming more important these days. > > Add a prefetch operation to reduce latency a bit on some > platforms like AMD EPYC 7B12. > > On more recent cpus, a stall happens when reading skb_shinfo(). > Avoiding it will require a more elaborate strategy. For my education, how do you catch such stalls? looking for specific perf events? Or just based on cycles spent in a given function/chunk of code? > Signed-off-by: Eric Dumazet Just to avoid doubts on my thoughts about this patch: Acked-by: Paolo Abeni