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 C3E1D46528; Mon, 7 Apr 2025 17:49:22 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id A5D2740A89; Mon, 7 Apr 2025 17:49:22 +0200 (CEST) Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) by mails.dpdk.org (Postfix) with ESMTP id 4132540273 for ; Mon, 7 Apr 2025 17:49:21 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1744040962; x=1775576962; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=zlEmyRpjZox6bW6l2tmnh/ij6120JNQyUhMAdLXV9qE=; b=KribpIRbqiW/5zoFvfnCFuSPH4tIiDmDlxgHY4mH21u1eDfpTy3ImHM8 Nm4hFArSvxhJrTCdZQBqAdhpiEL39kB3mijahIihBlCTyk3U1pxVyhxF/ tRookkEhgPI4j9IrPBKH7N6EOIeNEAJjZYYMPmSInEdzY3xDsav5gxyYn SBJerZtNvcS2mSQjzeTbFktB7pi/9KlP0iDTrdU13Kuac9OOcvMrfX4t4 64IzFuqdeJkxcVrjOustBD+RyGPTeEaJPtQXgDwh/3qSIP7v046I3DAuL PPd3WoSQ4Twhhzkv/RpITIdQwD0AA6Z+Ij+GI6vyh7WsiRFxqkATpW2nU g==; X-CSE-ConnectionGUID: voWpTGWRQJ6B2NPea8f6TQ== X-CSE-MsgGUID: KhP+kfdBQ3+Y8w/r+bhPrQ== X-IronPort-AV: E=McAfee;i="6700,10204,11397"; a="49287252" X-IronPort-AV: E=Sophos;i="6.15,194,1739865600"; d="scan'208";a="49287252" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Apr 2025 08:49:21 -0700 X-CSE-ConnectionGUID: HbzEGAiFRUKkGlYbISG8nQ== X-CSE-MsgGUID: Zbc1N66zTpOsnMTd9D4g7g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,194,1739865600"; d="scan'208";a="133149330" Received: from unknown (HELO silpixa00401385.ir.intel.com) ([10.237.214.31]) by fmviesa004.fm.intel.com with ESMTP; 07 Apr 2025 08:49:20 -0700 From: Bruce Richardson To: dev@dpdk.org Cc: Bruce Richardson , =?UTF-8?q?Morten=20Br=C3=B8rup?= Subject: [PATCH v2] doc: provide examples of using lcores EAL parameter Date: Mon, 7 Apr 2025 16:49:01 +0100 Message-ID: <20250407154901.2206824-1-bruce.richardson@intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250407132451.1101691-1-bruce.richardson@intel.com> References: <20250407132451.1101691-1-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 9cfbf7de84..aafe567bfa 100644 --- a/doc/guides/linux_gsg/eal_args.include.rst +++ b/doc/guides/linux_gsg/eal_args.include.rst @@ -29,6 +29,33 @@ 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