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 CEC224669F; Fri, 2 May 2025 17:12:19 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 8964340677; Fri, 2 May 2025 17:12:10 +0200 (CEST) Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) by mails.dpdk.org (Postfix) with ESMTP id 517334067D for ; Fri, 2 May 2025 17:12:08 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1746198729; x=1777734729; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=U6Y/5zlQcbfNged6ocupYBHYDfCjtOarOUxjoad3o9s=; b=j3RYYyKw3021swBVjCLLBMwGXyngZtW5D3oSZ+6CrrnTYHxliLVe8kxS KPGysjHIBzV1Z59OH/6CJ5PnEnCuFfe2u9ySlHfwfw/YcTKYuFaQ5xBWg PdIVREQVxxGSO+pJr/ElYBOq+844nf36Uuhod5Xat9Jh4Mzf0SH97IGOv TBkT2vVPHk5NUMSXpKajoYGyOdx+vmluB4ETKKgln1AXjv060XMdh96j2 zsB3KOlC/z4FsGULhQwWn1PBNk2QUzcFFDhJ0yfefdJe2ZXlSobSXqn8L CdTch6ItI4J2VsiaaHWl2e2jttGUy2ADNy1c5JlXLLKmcrAwoJ6CtaMZC w==; X-CSE-ConnectionGUID: WqVHUpfYTWawQouBn73cnw== X-CSE-MsgGUID: Zfw65ozaR+meUjDVJvPmqg== X-IronPort-AV: E=McAfee;i="6700,10204,11421"; a="47970525" X-IronPort-AV: E=Sophos;i="6.15,256,1739865600"; d="scan'208";a="47970525" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 May 2025 08:12:09 -0700 X-CSE-ConnectionGUID: 7kTXmftdQ625yExVnBr6jQ== X-CSE-MsgGUID: ojX0bTLkSNa8VLEUupsR2w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,256,1739865600"; d="scan'208";a="135172784" Received: from unknown (HELO silpixa00401385.ir.intel.com) ([10.237.214.31]) by orviesa007.jf.intel.com with ESMTP; 02 May 2025 08:12:07 -0700 From: Bruce Richardson To: dev@dpdk.org Cc: david.marchand@redhat.com, mb@smartsharesystems.com, stephen@networkplumber.org, Bruce Richardson Subject: [PATCH v3 3/4] doc: provide examples of using lcores EAL parameter Date: Fri, 2 May 2025 16:11:33 +0100 Message-ID: <20250502151134.536799-4-bruce.richardson@intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250502151134.536799-1-bruce.richardson@intel.com> References: <20250313113829.1480907-1-bruce.richardson@intel.com> <20250502151134.536799-1-bruce.richardson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 The "--lcores" EAL parameter has a very powerful syntax that can be used to provide precise control over lcore mappings. The docs however, only provided a minimal description of what it can do. Augment the docs by providing some examples of use of the option, and what the resulting core mappings would be. Signed-off-by: Bruce Richardson Acked-by: Morten Brørup --- doc/guides/linux_gsg/eal_args.include.rst | 27 +++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/doc/guides/linux_gsg/eal_args.include.rst b/doc/guides/linux_gsg/eal_args.include.rst index 01fe6a3006..d530215784 100644 --- a/doc/guides/linux_gsg/eal_args.include.rst +++ b/doc/guides/linux_gsg/eal_args.include.rst @@ -23,6 +23,33 @@ Lcore-related options The grouping ``()`` can be omitted for single element group. The ``@`` can be omitted if cpus and lcores have the same value. + Examples: + + ``--lcores=1-3``: Run threads on physical CPUs 1, 2 and 3, + with each thread having the same lcore id as the physical CPU id. + + ``--lcores=1@(1,2)``: Run a single thread with lcore id 1, + but with that thread bound to both physical CPUs 1 and 2, + so it can run on either, as determined by the operating system. + + ``--lcores='1@31,2@32,3@33'``: Run threads having internal lcore ids of 1, 2 and 3, + but with the threads being bound to physical CPUs 31, 32 and 33 respectively. + + ``--lcores='(1-3)@(31-33)'``: Run three threads with lcore ids 1, 2 and 3. + Unlike the previous example above, + each of these threads is not bound to one specific physical CPU, + but rather, all three threads are instead bound to the three physical CPUs 31, 32 and 33. + This means that each of the three threads can move between the physical CPUs 31-33, + as decided by the OS as the application runs. + + ``--lcores=(1-3)@20``: Run three threads, with lcore ids 1, 2 and 3, + where all three threads are bound to (can only run on) physical CPU 20. + +.. Note:: + Binding multiple DPDK lcores to a single physical CPU can cause problems with poor performance + or deadlock when using DPDK rings or memory pools or spinlocks. + Such a configuration should only be used with care. + .. Note:: At a given instance only one core option ``--lcores``, ``-l`` or ``-c`` can be used. -- 2.45.2