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From: David Marchand <david.marchand@redhat.com>
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 <kevin.laatz@intel.com>
Subject: [dpdk-dev] [PATCH v10 02/18] doc: describe how to enable AVX512
Date: Mon, 19 Oct 2020 15:48:42 +0200
Message-ID: <20201019134858.32507-3-david.marchand@redhat.com> (raw)
In-Reply-To: <20201019134858.32507-1-david.marchand@redhat.com>

From: Ciara Power <ciara.power@intel.com>

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 <ciara.power@intel.com>
Acked-by: Kevin Laatz <kevin.laatz@intel.com>
---
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


  parent reply	other threads:[~2020-10-19 13:50 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-19 13:48 [dpdk-dev] [PATCH v10 00/18] add max SIMD bitwidth to EAL David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 01/18] eal: control max SIMD bitwidth David Marchand
2020-10-19 13:48 ` David Marchand [this message]
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 03/18] net/i40e: check " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 04/18] net/axgbe: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 05/18] net/bnxt: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 06/18] net/enic: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 07/18] net/fm10k: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 08/18] net/iavf: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 09/18] net/ice: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 10/18] net/ixgbe: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 11/18] net/mlx5: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 12/18] net/virtio: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 13/18] distributor: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 14/18] member: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 15/18] efd: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 16/18] net: " David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 17/18] node: choose vector path at runtime David Marchand
2020-10-19 13:48 ` [dpdk-dev] [PATCH v10 18/18] acl: check max SIMD bitwidth David Marchand
2020-10-19 14:41 ` [dpdk-dev] [PATCH v10 00/18] add max SIMD bitwidth to EAL David Marchand

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