From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Thomas Monjalon" <thomas@monjalon.net>
Cc: "Ophir Munk" <ophirmu@nvidia.com>, <dev@dpdk.org>,
"Bruce Richardson" <bruce.richardson@intel.com>,
"Devendra Singh Rawat" <dsinghrawat@marvell.com>,
"Alok Prasad" <palok@marvell.com>,
"Matan Azrad" <matan@nvidia.com>,
"Lior Margalit" <lmargalit@nvidia.com>,
"Tyler Retzlaff" <roretzla@linux.microsoft.com>
Subject: RE: [RFC] lib: set/get max memzone segments
Date: Fri, 21 Apr 2023 17:19:05 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35D878AD@smartserver.smartshare.dk> (raw)
In-Reply-To: <7647463.lvqk35OSZv@thomas>
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Friday, 21 April 2023 16.57
>
> 21/04/2023 13:08, Morten Brørup:
> > > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > > Sent: Friday, 21 April 2023 10.35
> > > 20/04/2023 20:20, Tyler Retzlaff:
> > > > On Thu, Apr 20, 2023 at 09:43:28AM +0200, Thomas Monjalon wrote:
> > > > > 19/04/2023 16:51, Tyler Retzlaff:
> > > > > > On Wed, Apr 19, 2023 at 11:36:34AM +0300, Ophir Munk wrote:
> > > > > > > In current DPDK the RTE_MAX_MEMZONE definition is unconditionally
> hard
> > > > > > > coded as 2560. For applications requiring different values of
> this
> > > > > > > parameter – it is more convenient to set the max value via an rte
> API
> > > -
> > > > > > > rather than changing the dpdk source code per application. In
> many
> > > > > > > organizations, the possibility to compile a private DPDK library
> for a
> > > > > > > particular application does not exist at all. With this option
> there
> > > is
> > > > > > > no need to recompile DPDK and it allows using an in-box packaged
> DPDK.
> > > > > > > An example usage for updating the RTE_MAX_MEMZONE would be of an
> > > > > > > application that uses the DPDK mempool library which is based on
> DPDK
> > > > > > > memzone library. The application may need to create a number of
> > > > > > > steering tables, each of which will require its own mempool
> > > allocation.
> > > > > > > This commit is not about how to optimize the application usage of
> > > > > > > mempool nor about how to improve the mempool implementation based
> on
> > > > > > > memzone. It is about how to make the max memzone definition -
> run-
> > > time
> > > > > > > customized.
> > > > > > > This commit adds an API which must be called before
> rte_eal_init():
> > > > > > > rte_memzone_max_set(int max). If not called, the default memzone
> > > > > > > (RTE_MAX_MEMZONE) is used. There is also an API to query the
> > > effective
> > > > > > > max memzone: rte_memzone_max_get().
> > > > > > >
> > > > > > > Signed-off-by: Ophir Munk <ophirmu@nvidia.com>
> > > > > > > ---
> > > > > >
> > > > > > the use case of each application may want a different non-hard coded
> > > > > > value makes sense.
> > > > > >
> > > > > > it's less clear to me that requiring it be called before eal init
> makes
> > > > > > sense over just providing it as configuration to eal init so that it
> is
> > > > > > composed.
> > > > >
> > > > > Why do you think it would be better as EAL init option?
> > > > > From an API perspective, I think it is simpler to call a dedicated
> > > function.
> > > > > And I don't think a user wants to deal with it when starting the
> > > application.
> > > >
> > > > because a dedicated function that can be called detached from the eal
> > > > state enables an opportunity for accidental and confusing use outside
> > > > the correct context.
> > > >
> > > > i know the above prescribes not to do this but.
> > > >
> > > > now you can call set after eal init, but we protect about calling it
> > > > after init by failing. what do we do sensibly with the failure?
> > >
> > > It would be a developer mistake which could be fix during development
> stage
> > > very easily. I don't see a problem here.
> >
> > Why is this not just a command line parameter, like other EAL configuration
> options?
> >
> > Do any other pre-init APIs exist, or are you introducing a new design
> pattern for configuring EAL?
>
> Let's say it is a "new" design pattern, as discussed multiple times in
> previous years.
> But this one is only for the application,
> it is not a user configuration as in rte_eal_init(int argc, char **argv).
>
> > Any application can simply modify the command line parameters before calling
> EAL init. It doesn't need to pass the command line parameters as-is to EAL
> init.
>
> It is not very easy to use.
>
> > In other words: There is an existing design pattern for configuring EAL, why
> introduce a new design pattern?
>
> Because argc/argv is a bad pattern.
> We had multiple requests to avoid it.
> So when introducing a new option, it is better to avoid it.
>
> > If we want to expose APIs for configuring EAL instead of passing command
> line parameters, such APIs should be added for all EAL configuration
> parameters.
>
> The memzone parameter is not supposed to be configured by the user,
> so it does not make sense to expose it via argc/argv.
Good point! I didn't think about that; in hardware appliances, the user has no access to provide EAL command line parameters.
>
> > That would be nice, but I dislike that some EAL configuration parameters
> must be passed using one method and some other passed using another method.
>
> We asked multiple times for such rework.
High level directions/goals for DPDK, such as replacing EAL command line parameters with APIs, should be noted on the Roadmap web page.
> And the patches from Bruce to split some EAL parts are in this direction.
> If you want to propose some new functions to configure EAL, you are welcome.
OK. I retract my objection. :-)
next prev parent reply other threads:[~2023-04-21 15:19 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-19 8:36 Ophir Munk
2023-04-19 8:48 ` Ophir Munk
2023-04-19 13:42 ` [EXT] " Devendra Singh Rawat
2023-04-24 21:07 ` Ophir Munk
2023-04-19 14:42 ` Stephen Hemminger
2023-04-24 21:43 ` Ophir Munk
2023-04-19 14:51 ` Tyler Retzlaff
2023-04-20 7:43 ` Thomas Monjalon
2023-04-20 18:20 ` Tyler Retzlaff
2023-04-21 8:34 ` Thomas Monjalon
2023-04-21 11:08 ` Morten Brørup
2023-04-21 14:57 ` Thomas Monjalon
2023-04-21 15:19 ` Morten Brørup [this message]
2023-04-25 16:38 ` Ophir Munk
2023-04-25 13:46 ` Ophir Munk
2023-04-25 16:40 ` [RFC V2] " Ophir Munk
2023-05-03 7:26 ` [PATCH V3] " Ophir Munk
2023-05-03 21:41 ` Morten Brørup
2023-05-25 6:47 ` Ophir Munk
2023-05-04 7:27 ` David Marchand
2023-05-25 6:35 ` Ophir Munk
2023-05-18 15:54 ` Burakov, Anatoly
2023-05-25 6:43 ` Ophir Munk
2023-05-24 22:25 ` [PATCH v4] " Ophir Munk
2023-05-25 14:53 ` Burakov, Anatoly
2023-05-30 11:37 ` Ophir Munk
2023-05-26 9:55 ` David Marchand
2023-05-28 12:09 ` [EXT] " Alok Prasad
2023-05-30 13:32 ` Thomas Monjalon
2023-05-31 7:56 ` Ophir Munk
2023-05-31 7:52 ` [PATCH V5] " Ophir Munk
2023-05-31 8:41 ` [PATCH V6] " Ophir Munk
2023-06-05 8:52 ` [PATCH V7] " Ophir Munk
2023-06-05 10:50 ` [PATCH V8] " Ophir Munk
2023-06-05 16:50 ` Thomas Monjalon
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