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From: Olivier Matz <olivier.matz@6wind.com>
To: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
	Andrew Rybchenko <arybchenko@solarflare.com>,
	Gage Eads <gage.eads@intel.com>,
	"Artem V. Andreev" <artem.andreev@oktetlabs.ru>,
	Jerin Jacob <jerinj@marvell.com>,
	Nithin Dabilpuram <ndabilpuram@marvell.com>,
	Vamsi Attunuru <vattunuru@marvell.com>,
	Hemant Agrawal <hemant.agrawal@nxp.com>,
	David Marchand <david.marchand@redhat.com>,
	"Burakov, Anatoly" <anatoly.burakov@intel.com>,
	Bruce Richardson <bruce.richardson@intel.com>,
	dpdk-dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH dpdk-dev v3 2/2] mempool: use shared memzone for rte_mempool_ops
Date: Mon, 4 May 2020 09:42:27 +0200
Message-ID: <20200504074227.GA6327@platinum> (raw)
In-Reply-To: <CAMDZJNWCc4mRGkMZpNKtYR=r7B0_L2igF7E8bQgwLOEdKoPAVA@mail.gmail.com>

Hi,

On Tue, Apr 28, 2020 at 09:22:37PM +0800, Tonghao Zhang wrote:
> On Mon, Apr 27, 2020 at 8:51 PM Tonghao Zhang <xiangxia.m.yue@gmail.com> wrote:
> >
> > On Mon, Apr 27, 2020 at 7:40 PM Thomas Monjalon <thomas@monjalon.net> wrote:
> > >
> > > 27/04/2020 10:03, Tonghao Zhang:
> > > > On Fri, Apr 17, 2020 at 6:27 AM Thomas Monjalon <thomas@monjalon.net> wrote:
> > > > >
> > > > > 13/04/2020 16:21, xiangxia.m.yue@gmail.com:
> > > > > > The order of mempool initiation affects mempool index in the
> > > > > > rte_mempool_ops_table. For example, when building APPs with:
> > > > > >
> > > > > > $ gcc -lrte_mempool_bucket -lrte_mempool_ring ...
> > > > > >
> > > > > > The "bucket" mempool will be registered firstly, and its index
> > > > > > in table is 0 while the index of "ring" mempool is 1. DPDK
> > > > > > uses the mk/rte.app.mk to build APPs, and others, for example,
> > > > > > Open vSwitch, use the libdpdk.a or libdpdk.so to build it.
> > > > > > The mempool lib linked in dpdk and Open vSwitch is different.
> > > > >
> > > > > We are supposed to use pkg-config to link DPDK.
> > > > > Does the problem appear between a DPDK compiled with meson
> > > > > and an application linked with pkg-config information?
> > Hi Thomas,
> > The library mempool linked order can trigger that problem. but when
> > the library is loaded
> > dynamically, trigger that problem too.
> > as Olivier Matz said:
> > The fact that the ops index changes during mempool driver lifetime is
> > indeed frightening, especially knowning that this is a dynamic
> > registration that could happen at any moment in the life of the
> > application.
> >
> > the message in https://mails.dpdk.org/archives/dev/2020-March/159354.html
> Hi Thomas,
> For first patch, I guess we support a callback for other library, it
> make the codes much cleaner
> at eal layer. Otherwise, if we init for library, we may include their
> header file.
> There is a better solution ?

To summarize my understanding of the issu encountered by Tonghao:

Currently, it is not possible to call memzone_register() from an init
function (registered with RTE_INIT()). This is needed if we want to
store the list of registered mempool ops in a shared memory, available
from multiprocess.

Tonghao's patch 1/2 solves this issue. I tried to find alternatives
to this approach, but none of them seems satisfying:

- use RTE_PMD_REGISTER_VDEV() and rte_vdev_add_custom_scan() instead of
  RTE_INIT() in the MEMPOOL_REGISTER_OPS() macro to delay the
  initialization after eal_init(). This looks too complex (I made a POC
  of it, it someone is interested).

- synchronize mempool ops in shared memory when mempool_create() is
  called in the primary: this would probably works most of the time, but
  it is not a perfect solution as we cannot ensure that the primary
  application will create a mempool before the secondary comes up.

- introduce a mandatory call to rte_mempool_lib_init(): despite it's the
  usual way to initialize libs, this will break compatibility.

> > > > > If the problem really needs to be solved,
> > > > > the EAL patch (first of this series) needs to be discussed
> > > > > and reviewed carefully. I don't imagine it being done in 20.05.
> > > >

OK, let's discuss it once 20.05 is out.

Regards,
Olivier

  reply	other threads:[~2020-05-04  7:42 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-02  1:57 [dpdk-dev] [PATCH] mempool: sort the rte_mempool_ops by name xiangxia.m.yue
2020-03-02 13:45 ` Jerin Jacob
2020-03-04 13:17   ` Tonghao Zhang
2020-03-04 13:33     ` Jerin Jacob
2020-03-04 14:46       ` Tonghao Zhang
2020-03-04 15:14         ` Jerin Jacob
2020-03-04 15:25           ` Tonghao Zhang
2020-03-05  8:20 ` [dpdk-dev] [PATCH dpdk-dev v2] " xiangxia.m.yue
2020-03-05 16:57   ` Olivier Matz
2020-03-06 13:36 ` [dpdk-dev] [PATCH dpdk-dev v3] " xiangxia.m.yue
2020-03-06 13:37   ` Jerin Jacob
2020-03-07 12:51     ` Andrew Rybchenko
2020-03-07 12:54       ` Andrew Rybchenko
2020-03-09  3:01         ` Tonghao Zhang
2020-03-09  8:27           ` Olivier Matz
2020-03-09  8:55             ` Tonghao Zhang
2020-03-09  9:05               ` Olivier Matz
2020-03-09 13:15               ` David Marchand
2020-03-16  7:43                 ` Tonghao Zhang
2020-03-16  7:55                   ` Olivier Matz
2020-03-24  9:35             ` Andrew Rybchenko
2020-03-24 12:41               ` Tonghao Zhang
2020-04-09 10:52 ` [dpdk-dev] [PATCH dpdk-dev 1/2] eal: introduce last-init queue for libraries initialization xiangxia.m.yue
2020-04-09 10:53   ` [dpdk-dev] [PATCH dpdk-dev 2/2] mempool: use shared memzone for rte_mempool_ops xiangxia.m.yue
2020-04-09 11:31   ` [dpdk-dev] [PATCH dpdk-dev 1/2] eal: introduce last-init queue for libraries initialization Jerin Jacob
2020-04-09 15:04     ` Tonghao Zhang
2020-04-09 15:02 ` [dpdk-dev] [PATCH dpdk-dev v2 1/2] eal: introduce rte-init " xiangxia.m.yue
2020-04-09 15:02   ` [dpdk-dev] [PATCH dpdk-dev v2 2/2] mempool: use shared memzone for rte_mempool_ops xiangxia.m.yue
2020-04-10  6:18   ` [dpdk-dev] [PATCH dpdk-dev v2 1/2] eal: introduce rte-init queue for libraries initialization Jerin Jacob
2020-04-10 13:11     ` Jerin Jacob
2020-04-12  3:20       ` Tonghao Zhang
2020-04-12  3:32         ` Tonghao Zhang
2020-04-13 11:32           ` Jerin Jacob
2020-04-13 14:21 ` [dpdk-dev] [PATCH dpdk-dev v3 " xiangxia.m.yue
2020-04-13 14:21   ` [dpdk-dev] [PATCH dpdk-dev v3 2/2] mempool: use shared memzone for rte_mempool_ops xiangxia.m.yue
2020-04-16 22:27     ` Thomas Monjalon
2020-04-27  8:03       ` Tonghao Zhang
2020-04-27 11:40         ` Thomas Monjalon
2020-04-27 12:51           ` Tonghao Zhang
2020-04-28 13:22             ` Tonghao Zhang
2020-05-04  7:42               ` Olivier Matz [this message]
2021-03-25 14:24                 ` David Marchand
2020-04-23 13:38     ` Andrew Rybchenko
2020-04-27  5:23       ` Tonghao Zhang

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