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From: Olivier Matz <olivier.matz@6wind.com>
To: David Marchand <david.marchand@redhat.com>
Cc: dev@dpdk.org, jerinjacobk@gmail.com, bruce.richardson@intel.com,
	mdr@ashroe.eu, thomas@monjalon.net, arybchenko@solarflare.com,
	ktraynor@redhat.com, ian.stokes@intel.com, i.maximets@ovn.org,
	John McNamara <john.mcnamara@intel.com>,
	Marko Kovacevic <marko.kovacevic@intel.com>,
	Anatoly Burakov <anatoly.burakov@intel.com>,
	Neil Horman <nhorman@tuxdriver.com>
Subject: Re: [dpdk-dev] [PATCH v4 6/9] eal: register non-EAL threads as lcores
Date: Tue, 30 Jun 2020 12:07:17 +0200
Message-ID: <20200630100717.GF5869@platinum> (raw)
In-Reply-To: <20200626144736.11011-7-david.marchand@redhat.com>

On Fri, Jun 26, 2020 at 04:47:33PM +0200, David Marchand wrote:
> DPDK allows calling some part of its API from a non-EAL thread but this
> has some limitations.
> OVS (and other applications) has its own thread management but still
> want to avoid such limitations by hacking RTE_PER_LCORE(_lcore_id) and
> faking EAL threads potentially unknown of some DPDK component.
> 
> Introduce a new API to register non-EAL thread and associate them to a
> free lcore with a new NON_EAL role.
> This role denotes lcores that do not run DPDK mainloop and as such
> prevents use of rte_eal_wait_lcore() and consorts.
> 
> Multiprocess is not supported as the need for cohabitation with this new
> feature is unclear at the moment.
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
> ---
> Changes since v2:
> - refused multiprocess init once rte_thread_register got called, and
>   vice versa,
> - added warning on multiprocess in rte_thread_register doxygen,
> 
> Changes since v1:
> - moved cleanup on lcore role code in patch 5,
> - added unit test,
> - updated documentation,
> - changed naming from "external thread" to "registered non-EAL thread"
> 
> ---
>  MAINTAINERS                                   |   1 +
>  app/test/Makefile                             |   1 +
>  app/test/autotest_data.py                     |   6 +
>  app/test/meson.build                          |   2 +
>  app/test/test_lcores.c                        | 139 ++++++++++++++++++
>  doc/guides/howto/debug_troubleshoot.rst       |   5 +-
>  .../prog_guide/env_abstraction_layer.rst      |  22 +--
>  doc/guides/prog_guide/mempool_lib.rst         |   2 +-
>  lib/librte_eal/common/eal_common_lcore.c      |  50 ++++++-
>  lib/librte_eal/common/eal_common_mcfg.c       |  36 +++++
>  lib/librte_eal/common/eal_common_thread.c     |  33 +++++
>  lib/librte_eal/common/eal_memcfg.h            |  10 ++
>  lib/librte_eal/common/eal_private.h           |  18 +++
>  lib/librte_eal/freebsd/eal.c                  |   4 +
>  lib/librte_eal/include/rte_lcore.h            |  25 +++-
>  lib/librte_eal/linux/eal.c                    |   4 +
>  lib/librte_eal/rte_eal_version.map            |   2 +
>  lib/librte_mempool/rte_mempool.h              |  11 +-
>  18 files changed, 349 insertions(+), 22 deletions(-)
>  create mode 100644 app/test/test_lcores.c
> 

[...]

> diff --git a/app/test/test_lcores.c b/app/test/test_lcores.c
> new file mode 100644
> index 0000000000..864bcbade7
> --- /dev/null
> +++ b/app/test/test_lcores.c
> @@ -0,0 +1,139 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright (c) 2020 Red Hat, Inc.
> + */
> +
> +#include <pthread.h>
> +#include <string.h>
> +
> +#include <rte_lcore.h>
> +
> +#include "test.h"
> +
> +struct thread_context {
> +	enum { INIT, ERROR, DONE } state;
> +	bool lcore_id_any;
> +	pthread_t id;
> +	unsigned int *registered_count;
> +};
> +static void *thread_loop(void *arg)
> +{

missing an empty line here

> +	struct thread_context *t = arg;
> +	unsigned int lcore_id;
> +
> +	lcore_id = rte_lcore_id();
> +	if (lcore_id != LCORE_ID_ANY) {
> +		printf("Incorrect lcore id for new thread %u\n", lcore_id);
> +		t->state = ERROR;
> +	}
> +	rte_thread_register();
> +	lcore_id = rte_lcore_id();
> +	if ((t->lcore_id_any && lcore_id != LCORE_ID_ANY) ||
> +			(!t->lcore_id_any && lcore_id == LCORE_ID_ANY)) {
> +		printf("Could not register new thread, got %u while %sexpecting %u\n",
> +			lcore_id, t->lcore_id_any ? "" : "not ", LCORE_ID_ANY);
> +		t->state = ERROR;
> +	}

To check if rte_thread_register() succedeed, we need to look at
lcore_id. I wonder if rte_thread_register() shouldn't return the lcore
id on success, and -1 on error (rte_errno could be set to give some
info on the error).

The same could be done for rte_thread_init()

[...]

> diff --git a/lib/librte_eal/common/eal_common_thread.c b/lib/librte_eal/common/eal_common_thread.c
> index a7ae0691bf..1cbddc4b5b 100644
> --- a/lib/librte_eal/common/eal_common_thread.c
> +++ b/lib/librte_eal/common/eal_common_thread.c
> @@ -236,3 +236,36 @@ rte_ctrl_thread_create(pthread_t *thread, const char *name,
>  	pthread_join(*thread, NULL);
>  	return -ret;
>  }
> +
> +void
> +rte_thread_register(void)
> +{
> +	unsigned int lcore_id;
> +	rte_cpuset_t cpuset;
> +
> +	/* EAL init flushes all lcores, we can't register before. */
> +	assert(internal_config.init_complete == 1);
> +	if (pthread_getaffinity_np(pthread_self(), sizeof(cpuset),
> +			&cpuset) != 0)
> +		CPU_ZERO(&cpuset);
> +	lcore_id = eal_lcore_non_eal_allocate();
> +	if (lcore_id >= RTE_MAX_LCORE)
> +		lcore_id = LCORE_ID_ANY;
> +	rte_thread_init(lcore_id, &cpuset);
> +	if (lcore_id != LCORE_ID_ANY)
> +		RTE_LOG(DEBUG, EAL, "Registered non-EAL thread as lcore %u.\n",
> +			lcore_id);
> +}

So, in this case, the affinity of the pthread is kept and saved, in other
words there is no link between the lcore id and the affinity. It means we
are allowing an application to register lcores for dataplane with conflicting
affinities.

I wonder if it could be useful to have an API that automatically sets
the affinity according to the lcore_id. Or a function that creates a
pthread using the specified lcore id, and setting the correct affinity.
I could simplify the work for applications that want to create/destroy
dataplane threads dynamically.

This could be done later however, just an idea.

[...]
> diff --git a/lib/librte_eal/freebsd/eal.c b/lib/librte_eal/freebsd/eal.c
> index 13e5de006f..32a3d999b8 100644
> --- a/lib/librte_eal/freebsd/eal.c
> +++ b/lib/librte_eal/freebsd/eal.c
> @@ -424,6 +424,10 @@ rte_config_init(void)
>  		}
>  		if (rte_eal_config_reattach() < 0)
>  			return -1;
> +		if (!eal_mcfg_enable_multiprocess()) {
> +			RTE_LOG(ERR, EAL, "Primary process refused secondary attachment\n");
> +			return -1;
> +		}
>  		eal_mcfg_update_internal();
>  		break;
>  	case RTE_PROC_AUTO:
> diff --git a/lib/librte_eal/include/rte_lcore.h b/lib/librte_eal/include/rte_lcore.h
> index 3968c40693..43747e88df 100644
> --- a/lib/librte_eal/include/rte_lcore.h
> +++ b/lib/librte_eal/include/rte_lcore.h
> @@ -31,6 +31,7 @@ enum rte_lcore_role_t {
>  	ROLE_RTE,
>  	ROLE_OFF,
>  	ROLE_SERVICE,
> +	ROLE_NON_EAL,
>  };

If find the name ROLE_NON_EAL a bit heavy (this was also my impression
when reading the doc part).

I understand that there are several types of threads:

- eal (pthread created by eal): ROLE_RTE and ROLE_SERVICE
- unregistered (pthread not created by eal, and not registered): ROLE_OFF
  (note that ROLE_OFF also applies for unexistant threads)
- dynamic: pthread not created by eal, but registered

What about using ROLE_DYN ? I'm not sure about this name either, it's just
to open the discussion :)


  parent reply index

Thread overview: 126+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-10 14:44 [dpdk-dev] [PATCH 0/7] Register external threads as lcore David Marchand
2020-06-10 14:45 ` [dpdk-dev] [PATCH 1/7] eal: relocate per thread symbols to common David Marchand
2020-06-10 14:45 ` [dpdk-dev] [PATCH 2/7] eal: fix multiple definition of per lcore thread id David Marchand
2020-06-15  6:46   ` Kinsella, Ray
2020-06-10 14:45 ` [dpdk-dev] [PATCH 3/7] eal: introduce thread init helper David Marchand
2020-06-10 14:45 ` [dpdk-dev] [PATCH 4/7] eal: introduce thread uninit helper David Marchand
2020-06-10 14:45 ` [dpdk-dev] [PATCH 5/7] eal: register non-EAL threads as lcore David Marchand
2020-06-15  6:43   ` Kinsella, Ray
2020-06-10 14:45 ` [dpdk-dev] [PATCH 6/7] eal: dump lcores David Marchand
2020-06-15  6:40   ` Kinsella, Ray
2020-06-10 14:45 ` [dpdk-dev] [PATCH 7/7] eal: add lcore hotplug notifications David Marchand
2020-06-15  6:34   ` Kinsella, Ray
2020-06-15  7:13     ` David Marchand
2020-06-10 15:09 ` [dpdk-dev] [PATCH 0/7] Register external threads as lcore Jerin Jacob
2020-06-10 15:13   ` Bruce Richardson
2020-06-10 15:18   ` David Marchand
2020-06-10 15:33     ` Jerin Jacob
2020-06-15  7:11       ` David Marchand
2020-06-19 16:22 ` [dpdk-dev] [PATCH v2 0/9] Register non-EAL " David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 1/9] eal: relocate per thread symbols to common David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 2/9] eal: fix multiple definition of per lcore thread id David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 3/9] eal: introduce thread init helper David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 4/9] eal: introduce thread uninit helper David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 5/9] eal: move lcore role code David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 6/9] eal: register non-EAL threads as lcores David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 7/9] eal: add lcore init callbacks David Marchand
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 8/9] eal: add lcore iterators David Marchand
2020-06-20  2:21     ` Stephen Hemminger
2020-06-19 16:22   ` [dpdk-dev] [PATCH v2 9/9] mempool/bucket: handle non-EAL lcores David Marchand
2020-06-22 13:25 ` [dpdk-dev] [PATCH v3 0/9] Register non-EAL threads as lcore David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 1/9] eal: relocate per thread symbols to common David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 2/9] eal: fix multiple definition of per lcore thread id David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 3/9] eal: introduce thread init helper David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 4/9] eal: introduce thread uninit helper David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 5/9] eal: move lcore role code David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 6/9] eal: register non-EAL threads as lcores David Marchand
2020-06-22 15:49     ` Ananyev, Konstantin
2020-06-22 16:37       ` Ananyev, Konstantin
2020-06-23  7:49       ` David Marchand
2020-06-23  9:14         ` Bruce Richardson
2020-06-23 12:49           ` David Marchand
2020-06-23 13:15         ` Ananyev, Konstantin
2020-06-24  9:23           ` David Marchand
2020-06-24  9:56             ` Bruce Richardson
2020-06-24 10:08               ` Thomas Monjalon
2020-06-24 10:45                 ` Ananyev, Konstantin
2020-06-24 10:39             ` Ananyev, Konstantin
2020-06-24 10:48               ` David Marchand
2020-06-24 11:59                 ` Ananyev, Konstantin
2020-06-26 14:43                   ` David Marchand
2020-06-30 10:35                     ` Thomas Monjalon
2020-06-30 12:07                       ` Ananyev, Konstantin
2020-06-30 12:44                         ` Olivier Matz
2020-06-30 14:37                           ` Thomas Monjalon
2020-06-30 19:02                           ` Ananyev, Konstantin
2020-06-30 14:35                         ` Thomas Monjalon
2020-06-30 18:57                           ` Ananyev, Konstantin
2020-07-01  7:48                             ` David Marchand
2020-07-01 11:58                               ` Ananyev, Konstantin
2020-07-02 13:06                                 ` David Marchand
2020-07-03 15:15                                   ` Thomas Monjalon
2020-07-03 16:40                                   ` Ananyev, Konstantin
2020-07-04 15:00                                     ` David Marchand
2020-07-04 21:24                                       ` Ananyev, Konstantin
2020-06-23 17:02     ` Andrew Rybchenko
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 7/9] eal: add lcore init callbacks David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 8/9] eal: add lcore iterators David Marchand
2020-06-22 13:25   ` [dpdk-dev] [PATCH v3 9/9] mempool/bucket: handle non-EAL lcores David Marchand
2020-06-23 17:28     ` Andrew Rybchenko
2020-06-26 14:13       ` David Marchand
2020-06-26 14:34         ` Andrew Rybchenko
2020-06-26 14:47 ` [dpdk-dev] [PATCH v4 0/9] Register non-EAL threads as lcore David Marchand
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 1/9] eal: relocate per thread symbols to common David Marchand
2020-06-30  9:33     ` Olivier Matz
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 2/9] eal: fix multiple definition of per lcore thread id David Marchand
2020-06-30  9:34     ` Olivier Matz
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 3/9] eal: introduce thread init helper David Marchand
2020-06-30  9:37     ` Olivier Matz
2020-06-30 12:04       ` David Marchand
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 4/9] eal: introduce thread uninit helper David Marchand
2020-06-26 15:00     ` Jerin Jacob
2020-06-29  9:07       ` David Marchand
2020-06-29  8:59     ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-06-29  9:25       ` David Marchand
2020-06-30  9:42     ` [dpdk-dev] " Olivier Matz
2020-07-01  8:00       ` David Marchand
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 5/9] eal: move lcore role code David Marchand
2020-06-30  9:45     ` Olivier Matz
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 6/9] eal: register non-EAL threads as lcores David Marchand
2020-06-29 14:27     ` Ananyev, Konstantin
2020-06-30 10:07     ` Olivier Matz [this message]
2020-07-01  7:13       ` David Marchand
2020-07-01  9:11         ` Olivier Matz
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 7/9] eal: add lcore init callbacks David Marchand
2020-06-29 12:46     ` Ananyev, Konstantin
2020-06-30 10:09     ` Olivier Matz
2020-06-30 10:15     ` Olivier Matz
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 8/9] eal: add lcore iterators David Marchand
2020-06-30 10:11     ` Olivier Matz
2020-06-26 14:47   ` [dpdk-dev] [PATCH v4 9/9] mempool/bucket: handle non-EAL lcores David Marchand
2020-06-26 14:52     ` Andrew Rybchenko
2020-07-06 14:15 ` [dpdk-dev] [PATCH v5 00/10] Register non-EAL threads as lcore David Marchand
2020-07-06 14:15   ` [dpdk-dev] [PATCH v5 01/10] eal: relocate per thread symbols to common David Marchand
2020-07-06 14:15   ` [dpdk-dev] [PATCH v5 02/10] eal: fix multiple definition of per lcore thread id David Marchand
2020-07-06 14:15   ` [dpdk-dev] [PATCH v5 03/10] eal: introduce thread init helper David Marchand
2020-07-06 14:16   ` [dpdk-dev] [PATCH v5 04/10] eal: introduce thread uninit helper David Marchand
2020-07-06 14:16   ` [dpdk-dev] [PATCH v5 05/10] eal: move lcore role code David Marchand
2020-07-06 14:16   ` [dpdk-dev] [PATCH v5 06/10] eal: register non-EAL threads as lcores David Marchand
2020-07-06 14:16   ` [dpdk-dev] [PATCH v5 07/10] eal: add lcore init callbacks David Marchand
2020-07-06 14:16   ` [dpdk-dev] [PATCH v5 08/10] eal: add lcore iterators David Marchand
2020-07-06 14:16   ` [dpdk-dev] [PATCH v5 09/10] mempool/bucket: handle non-EAL lcores David Marchand
2020-07-06 14:16   ` [dpdk-dev] [PATCH v5 10/10] eal: add multiprocess disable API David Marchand
2020-07-06 20:52 ` [dpdk-dev] [PATCH v6 00/10] Register non-EAL threads as lcore David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 01/10] eal: relocate per thread symbols to common David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 02/10] eal: fix multiple definition of per lcore thread id David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 03/10] eal: introduce thread init helper David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 04/10] eal: introduce thread uninit helper David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 05/10] eal: move lcore role code David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 06/10] eal: register non-EAL threads as lcores David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 07/10] eal: add lcore init callbacks David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 08/10] eal: add lcore iterators David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 09/10] mempool/bucket: handle non-EAL lcores David Marchand
2020-07-06 20:52   ` [dpdk-dev] [PATCH v6 10/10] eal: add multiprocess disable API David Marchand
2020-07-06 23:22   ` [dpdk-dev] [PATCH v6 00/10] Register non-EAL threads as lcore Ananyev, Konstantin
2020-07-08 13:05     ` David Marchand
2020-07-08 13:06   ` David Marchand

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