DPDK-dev Archive on lore.kernel.org
 help / color / Atom feed
From: Olivier Matz <olivier.matz@6wind.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
	David Marchand <david.marchand@redhat.com>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"jerinjacobk@gmail.com" <jerinjacobk@gmail.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	"mdr@ashroe.eu" <mdr@ashroe.eu>,
	"ktraynor@redhat.com" <ktraynor@redhat.com>,
	"Stokes, Ian" <ian.stokes@intel.com>,
	"i.maximets@ovn.org" <i.maximets@ovn.org>,
	"Mcnamara, John" <john.mcnamara@intel.com>,
	"Kovacevic, Marko" <marko.kovacevic@intel.com>,
	"Burakov, Anatoly" <anatoly.burakov@intel.com>,
	Andrew Rybchenko <arybchenko@solarflare.com>,
	Neil Horman <nhorman@tuxdriver.com>
Subject: Re: [dpdk-dev] [PATCH v3 6/9] eal: register non-EAL threads as lcores
Date: Tue, 30 Jun 2020 14:44:09 +0200
Message-ID: <20200630124409.GL5869@platinum> (raw)
In-Reply-To: <BYAPR11MB3301B1A53373F3E929C200E49A6F0@BYAPR11MB3301.namprd11.prod.outlook.com>

On Tue, Jun 30, 2020 at 12:07:32PM +0000, Ananyev, Konstantin wrote:
> > 
> > 26/06/2020 16:43, David Marchand:
> > > On Wed, Jun 24, 2020 at 1:59 PM Ananyev, Konstantin
> > > <konstantin.ananyev@intel.com> wrote:
> > > > > > Do you mean - make this new dynamic-lcore API return an error if callied
> > > > > > from secondary process?
> > > > >
> > > > > Yes, and prohibiting from attaching a secondary process if dynamic
> > > > > lcore API has been used in primary.
> > > > > I intend to squash in patch 6:
> > > > > https://github.com/david-marchand/dpdk/commit/e5861ee734bfe2e4dc23d9b919b0db2a32a58aee
> > > >
> > > > But secondary process can attach before lcore_register, so we'll have some sort of inconsistency in behaviour.
> > >
> > > If the developer tries to use both features, he gets an ERROR log in
> > > the two init path.
> > > So whatever the order at runtime, we inform the developer (who did not
> > > read/understand the rte_thread_register() documentation) that what he
> > > is doing is unsupported.
> > 
> > I agree.
> > Before this patch, pinning a thread on a random core can
> > trigger some issues.
> > After this patch, register an external thread will
> > take care of logging errors in case of inconsistencies.
> > So the user will know he is doing something not supported
> > by the app.
> 
> I understand that, and return a meaningful error is definitely
> better the silent crash or memory corruption.
> The problem with that approach, as I said before, MP group
> behaviour becomes non-deterministic. 
> 
> > 
> > It is an nice improvement.
> > 
> > > > If we really  want to go ahead with such workaround -
> > 
> > It is not a workaround.
> > It is fixing some old issues and making clear what is really impossible.
> 
> The root cause of the problem is in our MP model design decisions:
> from one side we treat lcore_id as process local data, from other side
> in some shared data-structures we use lcore_id as an index.
> I think to fix it properly we need either: 
> make lcore_id data shared or stop using lcore_id as an index for shared data. 
> So from my perspective this approach is just one of possible workarounds.
> BTW, there is nothing wrong to have a workaround for the problem
> we are not ready to fix right now.
>  
> > > > probably better to introduce explicit EAL flag ( --single-process or so).
> > > > As Thomas and  Bruce suggested, if I understood them properly.
> > 
> > No I was thinking to maintain the tri-state information:
> > 	- secondary is possible
> > 	- secondary is attached
> > 	- secondary is forbidden
> 
> Ok, then I misunderstood you.
>  
> > Asking the user to use an option to forbid attaching a secondary process
> > is the same as telling him it is forbidden.
> 
> I don't think it is the same.
> On a live and complex system user can't always predict will the primary proc 
> use dynamic lcore and if it will at what particular moment.
> Same for secondary process launching - user might never start it,
> might start it straight after the primary one,
> or might be after several hours. 
> 
> > The error log is enough in my opinion.
> 
> I think it is better than nothing, but probably not the best one.
> Apart from possible non-consistent behaviour, it is quite restrictive:
> dynamic lcore_id wouldn't be available on any DPDK MP deployment.
> Which is a pity - I think it is a cool and useful feature.
>  
> What do you guys think about different approach:
> introduce new optional EAL parameter to restrict lcore_id
> values available for the process.
> 
> #let say to start primary proc that can use lcore_id=[0-99] only:
> dpdk_primary --lcore-allow=0-99 ... --file-prefix=xz1
> 
> #to start secondary one for it with allowed lcore_id=[100-109]:
> dpdk_secondary --lcore-allow=100-109 ... --file-prefix=xz1 --proc-type=secondary  
>  
> It is still a workaround, but that way we don't need to
> add any new limitations for dynamic lcores and secondary process usage. 
> Now it is up to user to decide would multiple-process use the same shared data
> and if so - split lcore_id space properly among them
> (same as he has to do now with static lcores).

A variant (more simple) of your approach could be to add
"--proc-type=standalone" to explicitly disable MP and enable dynamic thread
registration.



> > > A EAL flag is a stable API from the start, as there is nothing
> > > describing how we can remove one.
> > > So a new EAL flag for an experimental API/feature seems contradictory.
> > >
> > > Going with a new features status API... I think it is beyond this series.
> > >
> > > Thomas seems to suggest an automatic resolution when features conflict
> > > happens.. ?
> > 
> > I suggest allowing the maximum and raise an error when usage conflicts.
> > It seems this is what you did in v4.
> > 
> > > I'll send the v4, let's discuss it there if you want.
> > 
> 

  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 [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200630124409.GL5869@platinum \
    --to=olivier.matz@6wind.com \
    --cc=anatoly.burakov@intel.com \
    --cc=arybchenko@solarflare.com \
    --cc=bruce.richardson@intel.com \
    --cc=david.marchand@redhat.com \
    --cc=dev@dpdk.org \
    --cc=i.maximets@ovn.org \
    --cc=ian.stokes@intel.com \
    --cc=jerinjacobk@gmail.com \
    --cc=john.mcnamara@intel.com \
    --cc=konstantin.ananyev@intel.com \
    --cc=ktraynor@redhat.com \
    --cc=marko.kovacevic@intel.com \
    --cc=mdr@ashroe.eu \
    --cc=nhorman@tuxdriver.com \
    --cc=thomas@monjalon.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK-dev Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dpdk-dev/0 dpdk-dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dpdk-dev dpdk-dev/ https://lore.kernel.org/dpdk-dev \
		dev@dpdk.org
	public-inbox-index dpdk-dev

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.dpdk.dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git