From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 728CBA04DC; Mon, 19 Oct 2020 15:50:07 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 09854D027; Mon, 19 Oct 2020 15:49:28 +0200 (CEST) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by dpdk.org (Postfix) with ESMTP id C0026C848 for ; Mon, 19 Oct 2020 15:49:24 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603115363; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=y4bvEfo4owJI4qavGoQ3hQlxEZmrOU/ceb+afU1okCs=; b=aPvIn7a76IWFZ2M9AKVmbR75m7FrZXqc8BNQiOZ1vGm+0zno9wjNw0zpcNi8EuQ7JSSNEM /khQNMTtzD9Ej2/NUDphmL59RU/g6/C6Z1ZmDExck+XHcf2XvVFO+MjjPYToJhf+4ImOEz 8O4Op4QDJ6p86qidKVMctiQ1mNRJKKk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-205-_fcjS3SqO1m94CWYjejPeg-1; Mon, 19 Oct 2020 09:49:19 -0400 X-MC-Unique: _fcjS3SqO1m94CWYjejPeg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 77C87106F8DB; Mon, 19 Oct 2020 13:49:17 +0000 (UTC) Received: from dmarchan.remote.csb (unknown [10.40.195.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id 30F1C55775; Mon, 19 Oct 2020 13:49:15 +0000 (UTC) From: David Marchand To: dev@dpdk.org Cc: viktorin@rehivetech.com, ruifeng.wang@arm.com, jerinj@marvell.com, drc@linux.vnet.ibm.com, bruce.richardson@intel.com, konstantin.ananyev@intel.com, ciara.power@intel.com, Kevin Laatz Date: Mon, 19 Oct 2020 15:48:42 +0200 Message-Id: <20201019134858.32507-3-david.marchand@redhat.com> In-Reply-To: <20201019134858.32507-1-david.marchand@redhat.com> References: <20201019134858.32507-1-david.marchand@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david.marchand@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Subject: [dpdk-dev] [PATCH v10 02/18] doc: describe how to enable AVX512 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" From: Ciara Power This patch adds documentation on the usage of the max SIMD bitwidth EAL setting to enable AVX-512 at runtime. Signed-off-by: Ciara Power Acked-by: Kevin Laatz --- v6: Updated enum value. v4: Updated docs to reflect renamed enum. v3: - Added enum value for disabling use of max SIMD to doc. - Added entry to HowTo index. --- doc/guides/howto/avx512.rst | 36 ++++++++++++++++++++++++++++++++++++ doc/guides/howto/index.rst | 1 + 2 files changed, 37 insertions(+) create mode 100644 doc/guides/howto/avx512.rst diff --git a/doc/guides/howto/avx512.rst b/doc/guides/howto/avx512.rst new file mode 100644 index 0000000000..6c034b617d --- /dev/null +++ b/doc/guides/howto/avx512.rst @@ -0,0 +1,36 @@ +.. SPDX-License-Identifier: BSD-3-Clause + Copyright(c) 2020 Intel Corporation. + + +Using AVX-512 with DPDK +======================= + +AVX-512 is not used by default in DPDK, but it can be selected at runtime by apps through the use of EAL API, +and by the user with a commandline argument. DPDK has a setting for max SIMD bitwidth, +which can be modified and will then limit the vector path taken by the code. + + +Using the API in apps +--------------------- + +Apps can request DPDK uses AVX-512 at runtime, if it provides improved application performance. +This can be done by modifying the EAL setting for max SIMD bitwidth to 512, as by default it is 256, +which does not allow for AVX-512. + +.. code-block:: c + + rte_vect_set_max_simd_bitwidth(RTE_VECT_SIMD_512); + +This API should only be called once at initialization, before EAL init. +For more information on the possible enum values to use as a parameter, go to :ref:`max_simd_bitwidth`: + + +Using the command-line argument +--------------------------------------------- + +The user can select to use AVX-512 at runtime, using the following argument to set the max bitwidth:: + + ./app/dpdk-testpmd --force-max-simd-bitwidth=512 + +This will override any further changes to the max SIMD bitwidth in DPDK, +which is useful for testing purposes. diff --git a/doc/guides/howto/index.rst b/doc/guides/howto/index.rst index 5a97ea508c..c2a2c60ddb 100644 --- a/doc/guides/howto/index.rst +++ b/doc/guides/howto/index.rst @@ -20,3 +20,4 @@ HowTo Guides telemetry debug_troubleshoot openwrt + avx512 -- 2.23.0