From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 52FF545648; Thu, 18 Jul 2024 20:43:43 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 408784029B; Thu, 18 Jul 2024 20:43:43 +0200 (CEST) Received: from mail-pf1-f174.google.com (mail-pf1-f174.google.com [209.85.210.174]) by mails.dpdk.org (Postfix) with ESMTP id 0F25A4029B for ; Thu, 18 Jul 2024 20:43:41 +0200 (CEST) Received: by mail-pf1-f174.google.com with SMTP id d2e1a72fcca58-70b2a0542c2so121721b3a.3 for ; Thu, 18 Jul 2024 11:43:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20230601.gappssmtp.com; s=20230601; t=1721328221; x=1721933021; darn=dpdk.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=YhZKuVtcvY3zyL9CBlky1994+i7XXIxQzPUjZ4jz29o=; b=Jm9KAMgOWZvlf2QpLQNCDrtiHp5dAp5y0dxXiYGdwnM6TDIRLJXX+sw6c1xZT/6lET dVmxUtEgX70aXSxx3AnjoHlnVa/Qc4rBagzNq0VsmncnPiiFMNUQEFzUHnCiD3E2cDua rT4FCoCI3GjE7j39qifbTEUc5ehjh0bhQJTpOmKt41hKTgghaqQZco5WzvctxrU0sZcf b3ceXMvkF6n++U2ySwcSZRRKj5Z7vbxoRJSecIIiDrKZ0Aogs5bCG3caBPH7XAi6wX57 HftMaR2rQl9wamcioi69U5lpsK0ONxeggOLpwoYmf2SqXKlA5fw+NvR4IAXCP4MPrgxO Pl1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1721328221; x=1721933021; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=YhZKuVtcvY3zyL9CBlky1994+i7XXIxQzPUjZ4jz29o=; b=iFMF3ZRDrh9rgSn1WFdCRXrdGZj0vg17dNuXXXsXpCTtktAlCBzhK67rB9boVf3691 WuclKPkZqWWHQ5Oz6W3zUJKDgmXS4u2evYl3bw9+GR0rn8Mq4BTDwa7m/s+G38gOIajq Me2ghbDw0oiXVz3rqDeLVzBYXvoMnDUXmQKL4hjhDLLqGSEKnMs/F/otv1iKszNAR8E9 MdCFENXa46U3r6hr8ZdmPtzObK30jYe5vPIEpfvPbtpVOkVu/JXmM+moPXtSwLc++f8p p6VhhAB9MtmfRkCRaNURAE5aKYlO8VO5+RpLnMf6DESeI2BtLA1slbYvVEFelbnIzuzc Urjw== X-Gm-Message-State: AOJu0Yx3Th9VV8J4aXexiTjxGxyzzLDmGGHN/xXW6iU3vmpVh8CmZMF3 nVjdmpyLSByb40MYYpjhzamCB7nxUrOeTOlWxFwydde9bEcKHZD+GQpvcQlHMpNk8W+SBnc7Y3v DLfc= X-Google-Smtp-Source: AGHT+IEvqBynN0ugOJwfnACHtRGxDPjasjVRZ5hCdJLANoMcUGrcRpTbSeYPU0nWSJysVvo3i689wQ== X-Received: by 2002:a05:6a21:3418:b0:1c0:bce5:c19c with SMTP id adf61e73a8af0-1c3fdc6d16amr7577121637.12.1721328220888; Thu, 18 Jul 2024 11:43:40 -0700 (PDT) Received: from hermes.local (204-195-96-226.wavecable.com. [204.195.96.226]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fc0bc44f5fsm96401115ad.238.2024.07.18.11.43.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jul 2024 11:43:40 -0700 (PDT) From: Stephen Hemminger To: dev@dpdk.org Cc: Stephen Hemminger Subject: [PATCH 1/2] doc: add note about CPU 0 Date: Thu, 18 Jul 2024 11:43:25 -0700 Message-ID: <20240718184326.21375-1-stephen@networkplumber.org> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Linux (and probably BSD), CPU 0 can not be fully isolated because it receives timer interrupts and is used for other kernel related functions. The DPDK documentation should be updated to tell users to avoid polling on that CPU. Signed-off-by: Stephen Hemminger --- doc/guides/linux_gsg/enable_func.rst | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/doc/guides/linux_gsg/enable_func.rst b/doc/guides/linux_gsg/enable_func.rst index 5511640cb8..dc33ffc718 100644 --- a/doc/guides/linux_gsg/enable_func.rst +++ b/doc/guides/linux_gsg/enable_func.rst @@ -131,9 +131,14 @@ from running on those cores, it is possible to use the Linux kernel parameters ``isolcpus``, ``nohz_full``, ``irqaffinity`` to isolate them from the general Linux scheduler tasks. +.. note:: + + It is not recommended to use CPU core 0 for DPDK polling applications + because it can not be isolated from other system and kernel activity. + For example, if a given CPU has 0-7 cores -and DPDK applications are to run on logical cores 2, 4 and 6, -the following should be added to the kernel parameter list: +and DPDK applications are to run on logical cores 2, 4 and 6. +The following should be added to the kernel parameter list: .. code-block:: console -- 2.43.0