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From: Ruifeng Wang <Ruifeng.Wang@arm.com>
To: David Marchand <david.marchand@redhat.com>,
	Vladimir Medvedkin <vladimir.medvedkin@intel.com>,
	Bruce Richardson <bruce.richardson@intel.com>
Cc: John McNamara <john.mcnamara@intel.com>,
	Marko Kovacevic <marko.kovacevic@intel.com>,
	Ray Kinsella <mdr@ashroe.eu>, Neil Horman <nhorman@tuxdriver.com>,
	dev <dev@dpdk.org>,
	"Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	nd <nd@arm.com>, nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH v5 1/3] lib/lpm: integrate RCU QSBR
Date: Sat, 4 Jul 2020 17:00:10 +0000
Message-ID: <HE1PR0801MB2025BD6FCB4422B4D486D1E79E6B0@HE1PR0801MB2025.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <CAJFAV8x37tiCoVEUvFt0NSg-DYP6ELPBTfLWw4b7W-TZ-vE_3g@mail.gmail.com>

Hi David,

Sorry, I missed tracking of this thread.

> -----Original Message-----
> From: David Marchand <david.marchand@redhat.com>
> Sent: Monday, June 29, 2020 7:56 PM
> To: Ruifeng Wang <Ruifeng.Wang@arm.com>; Vladimir Medvedkin
> <vladimir.medvedkin@intel.com>; Bruce Richardson
> <bruce.richardson@intel.com>
> Cc: John McNamara <john.mcnamara@intel.com>; Marko Kovacevic
> <marko.kovacevic@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> <nhorman@tuxdriver.com>; dev <dev@dpdk.org>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; nd <nd@arm.com>
> Subject: Re: [dpdk-dev] [PATCH v5 1/3] lib/lpm: integrate RCU QSBR
> 
> On Mon, Jun 29, 2020 at 10:03 AM Ruifeng Wang <ruifeng.wang@arm.com>
> wrote:
> >
> > Currently, the tbl8 group is freed even though the readers might be
> > using the tbl8 group entries. The freed tbl8 group can be reallocated
> > quickly. This results in incorrect lookup results.
> >
> > RCU QSBR process is integrated for safe tbl8 group reclaim.
> > Refer to RCU documentation to understand various aspects of
> > integrating RCU library into other libraries.
> >
> > Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
> > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> > ---
> >  doc/guides/prog_guide/lpm_lib.rst  |  32 +++++++
> >  lib/librte_lpm/Makefile            |   2 +-
> >  lib/librte_lpm/meson.build         |   1 +
> >  lib/librte_lpm/rte_lpm.c           | 129 ++++++++++++++++++++++++++---
> >  lib/librte_lpm/rte_lpm.h           |  59 +++++++++++++
> >  lib/librte_lpm/rte_lpm_version.map |   6 ++
> >  6 files changed, 216 insertions(+), 13 deletions(-)
> >
> > diff --git a/doc/guides/prog_guide/lpm_lib.rst
> > b/doc/guides/prog_guide/lpm_lib.rst
> > index 1609a57d0..7cc99044a 100644
> > --- a/doc/guides/prog_guide/lpm_lib.rst
> > +++ b/doc/guides/prog_guide/lpm_lib.rst
> > @@ -145,6 +145,38 @@ depending on whether we need to move to the
> next table or not.
> >  Prefix expansion is one of the keys of this algorithm,  since it
> > improves the speed dramatically by adding redundancy.
> >
> > +Deletion
> > +~~~~~~~~
> > +
> > +When deleting a rule, a replacement rule is searched for. Replacement
> > +rule is an existing rule that has the longest prefix match with the rule to be
> deleted, but has smaller depth.
> > +
> > +If a replacement rule is found, target tbl24 and tbl8 entries are
> > +updated to have the same depth and next hop value with the
> replacement rule.
> > +
> > +If no replacement rule can be found, target tbl24 and tbl8 entries will be
> cleared.
> > +
> > +Prefix expansion is performed if the rule's depth is not exactly 24 bits or
> 32 bits.
> > +
> > +After deleting a rule, a group of tbl8s that belongs to the same tbl24 entry
> are freed in following cases:
> > +
> > +*   All tbl8s in the group are empty .
> > +
> > +*   All tbl8s in the group have the same values and with depth no greater
> than 24.
> > +
> > +Free of tbl8s have different behaviors:
> > +
> > +*   If RCU is not used, tbl8s are cleared and reclaimed immediately.
> > +
> > +*   If RCU is used, tbl8s are reclaimed when readers are in quiescent state.
> > +
> > +When the LPM is not using RCU, tbl8 group can be freed immediately
> > +even though the readers might be using the tbl8 group entries. This might
> result in incorrect lookup results.
> > +
> > +RCU QSBR process is integrated for safe tbl8 group reclaimation.
> > +Application has certain responsibilities while using this feature.
> > +Please refer to resource reclaimation framework of :ref:`RCU library
> <RCU_Library>` for more details.
> > +
> 
> Would the lpm6 library benefit from the same?
> Asking as I do not see much code shared between lpm and lpm6.
> 
Didn't look into lpm6. It may need separate integration with RCU since no shared code between lpm and lpm6 as you mentioned.

> [...]
> 
> > diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c index
> > 38ab512a4..41e9c49b8 100644
> > --- a/lib/librte_lpm/rte_lpm.c
> > +++ b/lib/librte_lpm/rte_lpm.c
> > @@ -1,5 +1,6 @@
> >  /* SPDX-License-Identifier: BSD-3-Clause
> >   * Copyright(c) 2010-2014 Intel Corporation
> > + * Copyright(c) 2020 Arm Limited
> >   */
> >
> >  #include <string.h>
> > @@ -245,13 +246,84 @@ rte_lpm_free(struct rte_lpm *lpm)
> >                 TAILQ_REMOVE(lpm_list, te, next);
> >
> >         rte_mcfg_tailq_write_unlock();
> > -
> > +#ifdef ALLOW_EXPERIMENTAL_API
> > +       if (lpm->dq)
> > +               rte_rcu_qsbr_dq_delete(lpm->dq); #endif
> 
> All DPDK code under lib/ is compiled with the ALLOW_EXPERIMENTAL_API
> flag set.
> There is no need to protect against this flag in rte_lpm.c.
> 
OK, I see. So DPDK libraries will always be compiled with the ALLOW_EXPERIMENTAL_API. It is application's 
choice to use experimental APIs. 
Will update in next version to remove the ALLOW_EXPERIMENTAL_API flag from rte_lpm.c and only keep the one in rte_lpm.h.

> [...]
> 
> > diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h index
> > b9d49ac87..7889f21b3 100644
> > --- a/lib/librte_lpm/rte_lpm.h
> > +++ b/lib/librte_lpm/rte_lpm.h
> 
> > @@ -130,6 +143,28 @@ struct rte_lpm {
> >                         __rte_cache_aligned; /**< LPM tbl24 table. */
> >         struct rte_lpm_tbl_entry *tbl8; /**< LPM tbl8 table. */
> >         struct rte_lpm_rule *rules_tbl; /**< LPM rules. */
> > +#ifdef ALLOW_EXPERIMENTAL_API
> > +       /* RCU config. */
> > +       struct rte_rcu_qsbr *v;         /* RCU QSBR variable. */
> > +       enum rte_lpm_qsbr_mode rcu_mode;/* Blocking, defer queue. */
> > +       struct rte_rcu_qsbr_dq *dq;     /* RCU QSBR defer queue. */
> > +#endif
> > +};
> 
> This is more a comment/question for the lpm maintainers.
> 
> Afaics, the rte_lpm structure is exported/public because of lookup which is
> inlined.
> But most of the structure can be hidden and stored in a private structure that
> would embed the exposed rte_lpm.
> The slowpath functions would only have to translate from publicly exposed
> to internal representation (via container_of).
> 
> This patch could do this and be the first step to hide the unneeded exposure
> of other fields (later/in 20.11 ?).
> 
To hide most of the structure is reasonable. 
Since it will break ABI, I can do that in 20.11.

> Thoughts?
> 
> 
> --
> David Marchand


  parent reply	other threads:[~2020-07-04 17:00 UTC|newest]

Thread overview: 137+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-22  6:34 [dpdk-dev] [RFC PATCH 0/3] RCU integration with LPM library Ruifeng Wang
2019-08-22  6:34 ` [dpdk-dev] [RFC PATCH 1/3] doc/rcu: add RCU integration design details Ruifeng Wang
2019-08-22  6:34 ` [dpdk-dev] [RFC PATCH 2/3] lib/ring: add peek API Ruifeng Wang
2019-08-22  6:34 ` [dpdk-dev] [RFC PATCH 3/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2019-08-23  1:23   ` Stephen Hemminger
2019-08-26  3:11     ` Ruifeng Wang (Arm Technology China)
2019-08-26  5:32       ` Honnappa Nagarahalli
2019-08-22 15:52 ` [dpdk-dev] [RFC PATCH 0/3] RCU integration with LPM library Honnappa Nagarahalli
2019-09-06  9:45 ` [dpdk-dev] [PATCH v2 0/6] " Ruifeng Wang
2019-09-06  9:45   ` [dpdk-dev] [PATCH v2 1/6] doc/rcu: add RCU integration design details Ruifeng Wang
2019-09-06 19:44     ` Honnappa Nagarahalli
2019-09-06  9:45   ` [dpdk-dev] [PATCH v2 2/6] lib/ring: add peek API Ruifeng Wang
2019-09-06  9:45   ` [dpdk-dev] [PATCH v2 3/6] lib/lpm: integrate RCU QSBR Ruifeng Wang
2019-09-06 19:44     ` Honnappa Nagarahalli
2019-09-18 16:15     ` Medvedkin, Vladimir
2019-09-19  6:17       ` Ruifeng Wang (Arm Technology China)
2019-09-06  9:45   ` [dpdk-dev] [PATCH v2 4/6] app/test: add test case for LPM RCU integration Ruifeng Wang
2019-09-06 19:45     ` Honnappa Nagarahalli
2019-09-06  9:45   ` [dpdk-dev] [PATCH v2 5/6] test/lpm: reset total time Ruifeng Wang
2019-09-18 16:17     ` Medvedkin, Vladimir
2019-09-19  6:22       ` Ruifeng Wang (Arm Technology China)
2019-09-06  9:45   ` [dpdk-dev] [PATCH v2 6/6] test/lpm: add RCU integration performance tests Ruifeng Wang
2019-09-06 19:46     ` Honnappa Nagarahalli
2019-10-01  6:29   ` [dpdk-dev] [PATCH v3 0/3] Add RCU reclamation APIs Honnappa Nagarahalli
2019-10-01  6:29     ` [dpdk-dev] [PATCH v3 1/3] lib/ring: add peek API Honnappa Nagarahalli
2019-10-02 18:42       ` Ananyev, Konstantin
2019-10-03 19:49         ` Honnappa Nagarahalli
2019-10-07  9:01           ` Ananyev, Konstantin
2019-10-09  4:25             ` Honnappa Nagarahalli
2019-10-10 15:09               ` Ananyev, Konstantin
2019-10-11  5:03                 ` Honnappa Nagarahalli
2019-10-11 14:41                   ` Ananyev, Konstantin
2019-10-11 18:28                     ` Honnappa Nagarahalli
2019-10-13 20:09                       ` Ananyev, Konstantin
2019-10-14  4:11                         ` Honnappa Nagarahalli
2019-10-01  6:29     ` [dpdk-dev] [PATCH v3 2/3] lib/rcu: add resource reclamation APIs Honnappa Nagarahalli
2019-10-02 17:39       ` Ananyev, Konstantin
2019-10-03  6:29         ` Honnappa Nagarahalli
2019-10-03 12:26           ` Ananyev, Konstantin
2019-10-04  6:07             ` Honnappa Nagarahalli
2019-10-07 10:46               ` Ananyev, Konstantin
2019-10-13  4:35                 ` Honnappa Nagarahalli
2019-10-02 18:50       ` Ananyev, Konstantin
2019-10-03  6:42         ` Honnappa Nagarahalli
2019-10-03 11:52           ` Ananyev, Konstantin
2019-10-04 19:01       ` Medvedkin, Vladimir
2019-10-07 13:11       ` Medvedkin, Vladimir
2019-10-13  3:02         ` Honnappa Nagarahalli
2019-10-15 16:48           ` Medvedkin, Vladimir
2019-10-18  3:47             ` Honnappa Nagarahalli
2019-10-01  6:29     ` [dpdk-dev] [PATCH v3 3/3] doc/rcu: add RCU integration design details Honnappa Nagarahalli
2020-03-29 20:57     ` [dpdk-dev] [PATCH v3 0/3] Add RCU reclamation APIs Thomas Monjalon
2020-03-30 17:37       ` Honnappa Nagarahalli
2020-04-03 18:41     ` [dpdk-dev] [PATCH v4 0/4] " Honnappa Nagarahalli
2020-04-03 18:41       ` [dpdk-dev] [PATCH v4 1/4] lib/rcu: add resource " Honnappa Nagarahalli
2020-04-07 17:39         ` Ananyev, Konstantin
2020-04-19 23:22           ` Honnappa Nagarahalli
2020-04-20  8:19             ` Ananyev, Konstantin
2020-04-03 18:41       ` [dpdk-dev] [PATCH v4 2/4] test/rcu: test cases for RCU defer queue APIs Honnappa Nagarahalli
2020-04-03 18:41       ` [dpdk-dev] [PATCH v4 3/4] doc/rcu: add RCU integration design details Honnappa Nagarahalli
2020-04-03 18:41       ` [dpdk-dev] [PATCH v4 4/4] lib/rcu: add additional debug logs Honnappa Nagarahalli
2020-04-22  3:30     ` [dpdk-dev] [PATCH v5 0/4] Add RCU reclamation APIs Honnappa Nagarahalli
2020-04-22  3:30       ` [dpdk-dev] [PATCH v5 1/4] lib/rcu: add resource " Honnappa Nagarahalli
2020-04-22  8:36         ` Ananyev, Konstantin
2020-04-22  8:42           ` David Marchand
2020-04-22  8:51             ` David Marchand
2020-04-22  9:26               ` Ananyev, Konstantin
2020-04-22  3:30       ` [dpdk-dev] [PATCH v5 2/4] test/rcu: test cases for RCU defer queue APIs Honnappa Nagarahalli
2020-04-22  8:27         ` Ananyev, Konstantin
2020-04-22  3:30       ` [dpdk-dev] [PATCH v5 3/4] doc/rcu: add RCU integration design details Honnappa Nagarahalli
2020-04-22  3:30       ` [dpdk-dev] [PATCH v5 4/4] lib/rcu: add additional debug logs Honnappa Nagarahalli
2020-04-22  8:25         ` Ananyev, Konstantin
2020-04-22 18:46       ` [dpdk-dev] [PATCH v5 0/4] Add RCU reclamation APIs David Marchand
2019-10-01 18:28   ` [dpdk-dev] [PATCH v3 0/3] RCU integration with LPM library Honnappa Nagarahalli
2019-10-01 18:28     ` [dpdk-dev] [PATCH v3 1/3] lib/lpm: integrate RCU QSBR Honnappa Nagarahalli
2019-10-04 16:05       ` Medvedkin, Vladimir
2019-10-09  3:48         ` Honnappa Nagarahalli
2019-10-07  9:21       ` Ananyev, Konstantin
2019-10-13  4:36         ` Honnappa Nagarahalli
2019-10-15 11:15           ` Ananyev, Konstantin
2019-10-18  3:32             ` Honnappa Nagarahalli
2019-10-01 18:28     ` [dpdk-dev] [PATCH v3 2/3] app/test: add test case for LPM RCU integration Honnappa Nagarahalli
2019-10-01 18:28     ` [dpdk-dev] [PATCH v3 3/3] test/lpm: add RCU integration performance tests Honnappa Nagarahalli
2019-10-02 13:02       ` Aaron Conole
2019-10-03  9:09         ` Bruce Richardson
2020-06-08  5:16   ` [dpdk-dev] [PATCH v4 0/3] RCU integration with LPM library Ruifeng Wang
2020-06-08  5:16     ` [dpdk-dev] [PATCH v4 1/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2020-06-08 18:46       ` Honnappa Nagarahalli
2020-06-18 17:36         ` Medvedkin, Vladimir
2020-06-18 17:21       ` Medvedkin, Vladimir
2020-06-22  5:46         ` Ruifeng Wang
2020-06-23  4:34           ` Honnappa Nagarahalli
2020-06-08  5:16     ` [dpdk-dev] [PATCH v4 2/3] test/lpm: add LPM RCU integration functional tests Ruifeng Wang
2020-06-08  5:16     ` [dpdk-dev] [PATCH v4 3/3] test/lpm: add RCU integration performance tests Ruifeng Wang
2020-06-29  8:02   ` [dpdk-dev] [PATCH v5 0/3] RCU integration with LPM library Ruifeng Wang
2020-06-29  8:02     ` [dpdk-dev] [PATCH v5 1/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2020-06-29 11:56       ` David Marchand
2020-06-29 12:55         ` Bruce Richardson
2020-06-30 10:35           ` Kinsella, Ray
2020-07-03  7:43         ` David Marchand
2020-07-04 17:00         ` Ruifeng Wang [this message]
2020-06-30 10:33       ` Kinsella, Ray
2020-06-29  8:02     ` [dpdk-dev] [PATCH v5 2/3] test/lpm: add LPM RCU integration functional tests Ruifeng Wang
2020-06-29  8:03     ` [dpdk-dev] [PATCH v5 3/3] test/lpm: add RCU integration performance tests Ruifeng Wang
2020-07-07 14:40   ` [dpdk-dev] [PATCH v6 0/3] RCU integration with LPM library Ruifeng Wang
2020-07-07 14:40     ` [dpdk-dev] [PATCH v6 1/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2020-07-07 14:40     ` [dpdk-dev] [PATCH v6 2/3] test/lpm: add LPM RCU integration functional tests Ruifeng Wang
2020-07-07 14:40     ` [dpdk-dev] [PATCH v6 3/3] test/lpm: add RCU integration performance tests Ruifeng Wang
2020-07-07 15:15   ` [dpdk-dev] [PATCH v7 0/3] RCU integration with LPM library Ruifeng Wang
2020-07-07 15:15     ` [dpdk-dev] [PATCH v7 1/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2020-07-08 12:36       ` Medvedkin, Vladimir
2020-07-08 14:30       ` David Marchand
2020-07-08 15:34         ` Ruifeng Wang
2020-07-07 15:15     ` [dpdk-dev] [PATCH v7 2/3] test/lpm: add LPM RCU integration functional tests Ruifeng Wang
2020-07-08 12:37       ` Medvedkin, Vladimir
2020-07-08 14:00         ` Ruifeng Wang
2020-07-07 15:15     ` [dpdk-dev] [PATCH v7 3/3] test/lpm: add RCU integration performance tests Ruifeng Wang
2020-07-08 12:37       ` Medvedkin, Vladimir
2020-07-08 14:07         ` Ruifeng Wang
2020-07-09  8:02   ` [dpdk-dev] [PATCH v8 0/3] RCU integration with LPM library Ruifeng Wang
2020-07-09  8:02     ` [dpdk-dev] [PATCH v8 1/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2020-07-09 11:49       ` David Marchand
2020-07-09 14:35         ` Ruifeng Wang
2020-07-09  8:02     ` [dpdk-dev] [PATCH v8 2/3] test/lpm: add LPM RCU integration functional tests Ruifeng Wang
2020-07-09  8:02     ` [dpdk-dev] [PATCH v8 3/3] test/lpm: add RCU integration performance tests Ruifeng Wang
2020-07-09 15:42   ` [dpdk-dev] [PATCH v9 0/3] RCU integration with LPM library Ruifeng Wang
2020-07-09 15:42     ` [dpdk-dev] [PATCH v9 1/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2020-07-09 15:42     ` [dpdk-dev] [PATCH v9 2/3] test/lpm: add LPM RCU integration functional tests Ruifeng Wang
2020-07-09 15:42     ` [dpdk-dev] [PATCH v9 3/3] test/lpm: add RCU integration performance tests Ruifeng Wang
2020-07-10  2:22   ` [dpdk-dev] [PATCH v10 0/3] RCU integration with LPM library Ruifeng Wang
2020-07-10  2:22     ` [dpdk-dev] [PATCH v10 1/3] lib/lpm: integrate RCU QSBR Ruifeng Wang
2020-07-10  2:29       ` Ruifeng Wang
2020-07-10  2:22     ` [dpdk-dev] [PATCH v10 2/3] test/lpm: add LPM RCU integration functional tests Ruifeng Wang
2020-07-10  2:22     ` [dpdk-dev] [PATCH v10 3/3] test/lpm: add RCU integration performance tests Ruifeng Wang
2020-07-10  2:29       ` Ruifeng Wang
2020-07-10 12:21     ` [dpdk-dev] [PATCH v10 0/3] RCU integration with LPM library David Marchand
2020-07-10 14:34       ` Ruifeng Wang

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