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From: David Marchand <david.marchand@redhat.com>
To: dev@dpdk.org
Cc: anatoly.burakov@intel.com, jerinj@marvell.com,
	thomas@monjalon.net, John McNamara <john.mcnamara@intel.com>,
	Marko Kovacevic <marko.kovacevic@intel.com>
Subject: [dpdk-dev] [PATCH v4 4/4] eal: select IOVA as VA mode for default case
Date: Mon, 22 Jul 2019 14:56:53 +0200
Message-ID: <1563800213-29839-5-git-send-email-david.marchand@redhat.com> (raw)
In-Reply-To: <1563800213-29839-1-git-send-email-david.marchand@redhat.com>

From: Jerin Jacob <jerinj@marvell.com>

When bus layer reports the preferred mode as RTE_IOVA_DC then
select the RTE_IOVA_VA mode:

- All drivers work in RTE_IOVA_VA mode, irrespective of physical
address availability.

- By default, a mempool asks for IOVA-contiguous memory using
RTE_MEMZONE_IOVA_CONTIG. This is slow in RTE_IOVA_PA mode and it
may affect the application boot time.

Signed-off-by: Jerin Jacob <jerinj@marvell.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>
---
Changelog since v3:
- moved the explanations on RTE_IOVA_VA choice in the note section,
- reworded the comments on the PCI driver flag,

---
 doc/guides/prog_guide/env_abstraction_layer.rst | 22 ++++++++++++++++++++--
 lib/librte_eal/linux/eal/eal.c                  |  6 ++----
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst b/doc/guides/prog_guide/env_abstraction_layer.rst
index 1d63675..1487ea5 100644
--- a/doc/guides/prog_guide/env_abstraction_layer.rst
+++ b/doc/guides/prog_guide/env_abstraction_layer.rst
@@ -445,11 +445,29 @@ kernels.
 - if the preferred mode is RTE_IOVA_PA but there is no access to Physical
   Addresses, then EAL init fails early, since later probing of the devices
   would fail anyway,
-- if the preferred mode is RTE_IOVA_DC then based on the Physical Addresses
-  availability, the preferred mode is adjusted to RTE_IOVA_PA or RTE_IOVA_VA.
+- if the preferred mode is RTE_IOVA_DC then EAL selects the RTE_IOVA_VA mode.
   In the case when the buses had disagreed on the IOVA Mode at the first step,
   part of the buses won't work because of this decision.
 
+.. note::
+
+    The RTE_IOVA_VA mode is selected as the default for the following reasons:
+
+    - All drivers are expected to work in RTE_IOVA_VA mode, irrespective of
+      physical address availability.
+    - By default, the mempool, first asks for IOVA-contiguous memory using
+      ``RTE_MEMZONE_IOVA_CONTIG``. This is slow in RTE_IOVA_PA mode and it may
+      affect the application boot time.
+    - It is easy to enable large amount of IOVA-contiguous memory use-cases
+      with IOVA in VA mode.
+
+    It is expected that all PCI drivers work in both RTE_IOVA_PA and
+    RTE_IOVA_VA modes.
+
+    If a PCI driver does not support RTE_IOVA_PA mode, the
+    ``RTE_PCI_DRV_NEED_IOVA_AS_VA`` flag is used to dictate that this PCI
+    driver can only work in RTE_IOVA_VA mode.
+
 IOVA Mode Configuration
 ~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/lib/librte_eal/linux/eal/eal.c b/lib/librte_eal/linux/eal/eal.c
index 2e5499f..34db787 100644
--- a/lib/librte_eal/linux/eal/eal.c
+++ b/lib/librte_eal/linux/eal/eal.c
@@ -1061,10 +1061,8 @@ static void rte_eal_init_alert(const char *msg)
 		enum rte_iova_mode iova_mode = rte_bus_get_iommu_class();
 
 		if (iova_mode == RTE_IOVA_DC) {
-			iova_mode = phys_addrs ? RTE_IOVA_PA : RTE_IOVA_VA;
-			RTE_LOG(DEBUG, EAL,
-				"Buses did not request a specific IOVA mode, using '%s' based on physical addresses availability.\n",
-				phys_addrs ? "PA" : "VA");
+			iova_mode = RTE_IOVA_VA;
+			RTE_LOG(DEBUG, EAL, "Buses did not request a specific IOVA mode, select IOVA as VA mode.\n");
 		}
 #ifdef RTE_LIBRTE_KNI
 		/* Workaround for KNI which requires physical address to work */
-- 
1.8.3.1


  parent reply index

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-10 21:48 [dpdk-dev] [PATCH 0/2] Fixes on IOVA mode selection David Marchand
2019-07-10 21:48 ` [dpdk-dev] [PATCH 1/2] Revert "bus/pci: add Mellanox kernel driver type" David Marchand
2019-07-16 10:37   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-10 21:48 ` [dpdk-dev] [PATCH 2/2] eal: fix IOVA mode selection as VA for pci drivers David Marchand
2019-07-11 14:40   ` Thomas Monjalon
2019-07-12  8:05     ` Jerin Jacob Kollanukkaran
2019-07-12 11:03   ` Burakov, Anatoly
2019-07-12 12:43     ` Thomas Monjalon
2019-07-12 12:58       ` Burakov, Anatoly
2019-07-12 13:19         ` Bruce Richardson
2019-07-15 14:26       ` Jerin Jacob Kollanukkaran
2019-07-15 15:03         ` Thomas Monjalon
2019-07-15 15:35           ` Jerin Jacob Kollanukkaran
2019-07-15 16:06             ` Thomas Monjalon
2019-07-15 16:27               ` Jerin Jacob Kollanukkaran
2019-07-16 13:46 ` [dpdk-dev] [PATCH v2 0/4] Fixes on IOVA mode selection jerinj
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 1/4] Revert "bus/pci: add Mellanox kernel driver type" jerinj
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 2/4] eal: fix IOVA mode selection as VA for pci drivers jerinj
2019-07-16 14:26     ` Burakov, Anatoly
2019-07-16 15:07       ` Jerin Jacob Kollanukkaran
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 3/4] eal: change RTE_PCI_DRV_IOVA_AS_VA flag name jerinj
2019-07-16 13:46   ` [dpdk-dev] [PATCH v2 4/4] eal: select IOVA mode as VA for default case jerinj
2019-07-16 14:33     ` Burakov, Anatoly
2019-07-17  8:33       ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-17 12:38         ` Burakov, Anatoly
2019-07-17 14:04           ` Jerin Jacob Kollanukkaran
2019-07-18  6:45   ` [dpdk-dev] [PATCH v3 0/4] Fixes on IOVA mode selection jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 1/4] Revert "bus/pci: add Mellanox kernel driver type" jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 2/4] eal: fix IOVA mode selection as VA for pci drivers jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 3/4] eal: change RTE_PCI_DRV_IOVA_AS_VA flag name jerinj
2019-07-18  6:45     ` [dpdk-dev] [PATCH v3 4/4] eal: select IOVA mode as VA for default case jerinj
2019-07-22 11:28     ` [dpdk-dev] [PATCH v3 0/4] Fixes on IOVA mode selection David Marchand
2019-07-22 12:56 ` [dpdk-dev] [PATCH v4 " David Marchand
2019-07-22 12:56   ` [dpdk-dev] [PATCH v4 1/4] Revert "bus/pci: add Mellanox kernel driver type" David Marchand
2019-07-22 12:56   ` [dpdk-dev] [PATCH v4 2/4] eal: fix IOVA mode selection as VA for PCI drivers David Marchand
2019-11-25  9:33     ` Ferruh Yigit
2019-11-25 10:22       ` Thomas Monjalon
2019-11-25 12:03         ` Ferruh Yigit
2019-11-25 12:36           ` David Marchand
2019-11-25 12:58             ` Burakov, Anatoly
2019-11-25 14:29               ` Thomas Monjalon
2019-11-25 11:07       ` Jerin Jacob
2019-07-22 12:56   ` [dpdk-dev] [PATCH v4 3/4] drivers: change IOVA as VA PCI flag name David Marchand
2019-07-22 12:56   ` David Marchand [this message]
2019-07-22 15:53   ` [dpdk-dev] [PATCH v4 0/4] Fixes on IOVA mode selection Thomas Monjalon
2019-07-23  3:35     ` Stojaczyk, Dariusz
2019-07-23  4:18       ` Jerin Jacob Kollanukkaran
2019-07-23  4:54         ` Stojaczyk, Dariusz
2019-07-23  5:27           ` Jerin Jacob Kollanukkaran
2019-07-23  7:21             ` Thomas Monjalon
2019-07-23  9:57             ` Burakov, Anatoly
2019-07-23 10:25               ` Thomas Monjalon
2019-07-23 13:56                 ` Burakov, Anatoly
2019-07-23 14:24                   ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-23 14:29                   ` [dpdk-dev] " Burakov, Anatoly
2019-07-23 14:36                     ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2019-07-23 15:47                       ` Burakov, Anatoly

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