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[24.6.151.244]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21f3683d8a7sm12843885ad.148.2025.02.06.06.01.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2025 06:01:30 -0800 (PST) Date: Thu, 6 Feb 2025 06:01:27 -0800 From: Joe Damato To: Samiullah Khawaja Cc: Dave Taht , Jakub Kicinski , "David S . Miller" , Eric Dumazet , Paolo Abeni , almasrymina@google.com, netdev@vger.kernel.org Subject: Re: [PATCH net-next v3 0/4] Add support to do threaded napi busy poll Message-ID: Mail-Followup-To: Joe Damato , Samiullah Khawaja , Dave Taht , Jakub Kicinski , "David S . Miller" , Eric Dumazet , Paolo Abeni , almasrymina@google.com, netdev@vger.kernel.org References: <20250205001052.2590140-1-skhawaja@google.com> 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-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Feb 05, 2025 at 09:49:04PM -0800, Samiullah Khawaja wrote: > On Wed, Feb 5, 2025 at 9:36 PM Dave Taht wrote: > > > > I have often wondered the effects of reducing napi poll weight from 64 > > to 16 or less. > Yes, that is Interesting. I think higher weight would allow it to > fetch more descriptors doing more batching but then packets are pushed > up the stack late. A lower value would push packet up the stack > quicker, but then if the core is being shared with the application > processing thread then the descriptors will spend more time in the NIC > queue. Seems testable? > > > > Also your test shows an increase in max latency... > > > > latency_max=0.200182942 > I noticed this anomaly and my guess is that it is a packet drop and > this is basically a retransmit timeout. Going through tcpdumps to > confirm. Can you call out anomalies like this more explicitly and explain why they occur? If it weren't for Dave's response, I would have missed this.