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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-441b2b28dadsm24303915e9.40.2025.04.30.05.37.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Apr 2025 05:37:35 -0700 (PDT) Date: Wed, 30 Apr 2025 13:37:34 +0100 From: David Laight To: Martin Karsten Cc: Willem de Bruijn , Joe Damato , Samiullah Khawaja , Jakub Kicinski , "David S . Miller" , Eric Dumazet , Paolo Abeni , almasrymina@google.com, willemb@google.com, netdev@vger.kernel.org Subject: Re: [PATCH net-next v5 0/4] Add support to do threaded napi busy poll Message-ID: <20250430133734.0e78a746@pumpkin> In-Reply-To: <5fa8c9b8-527c-4392-9c9f-4e1e93ab5326@uwaterloo.ca> References: <20250424200222.2602990-1-skhawaja@google.com> <52e7cf72-6655-49ed-984c-44bd1ecb0d95@uwaterloo.ca> <680fb23bb1953_23f881294d9@willemb.c.googlers.com.notmuch> <680fc1f210fdf_246a60294b2@willemb.c.googlers.com.notmuch> <5fa8c9b8-527c-4392-9c9f-4e1e93ab5326@uwaterloo.ca> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 28 Apr 2025 14:05:17 -0400 Martin Karsten wrote: ... > That's not the same. The existing busy-poll mechanism still needs an > application thread. This thing will just go off and spin, whether > there's an application or not. I think this (and elsewhere) should be 'busy spin' not 'busy poll'. That would make it much more obvious that it really is a cpu intensive spin loop. Note that on some cpu all the 'cores' run at the same speed. So that putting one into a 'spin' will cause the frequency of all of them to increase - thus speeding up a benchmark. Rather the opposite of tests where a cpu busy thread (doing work) gets bounced around physical cpu - so keeps being run on ones running a low clock speed. David