Re: [dpdk-dev] [PATCH] eal: change max hugepage sizes to 4

From: David Marchand <david.marchand@redhat.com>
To: Gagandeep Singh <G.Singh@nxp.com>,
	Hemant Agrawal <hemant.agrawal@nxp.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
	"dev@dpdk.org" <dev@dpdk.org>,
	 "Burakov, Anatoly" <anatoly.burakov@intel.com>,
	Olivier Matz <olivier.matz@6wind.com>,
	 Andrew Rybchenko <arybchenko@solarflare.com>,
	Nipun Gupta <nipun.gupta@nxp.com>,
	"honnappa.nagarahalli@arm.com" <honnappa.nagarahalli@arm.com>,
	Steve Capper <steve.capper@arm.com>,
	 "jerinj@marvell.com" <jerinj@marvell.com>,
	 "bruce.richardson@intel.com" <bruce.richardson@intel.com>,
	"gavin.hu@arm.com" <gavin.hu@arm.com>,
	 "konstantin.ananyev@intel.com" <konstantin.ananyev@intel.com>,
	 "drc@linux.vnet.ibm.com" <drc@linux.vnet.ibm.com>
Subject: Re: [dpdk-dev] [PATCH] eal: change max hugepage sizes to 4
Date: Thu, 8 Aug 2019 11:22:42 +0200	[thread overview]
Message-ID: <CAJFAV8zh696Xe0S21hv5HDSL_jk9b4TKPF29Wf+g=y-HXy-ujg@mail.gmail.com> (raw)
In-Reply-To: <VE1PR04MB63652CADB8785B3353BBFBE8E1D70@VE1PR04MB6365.eurprd04.prod.outlook.com>

On Thu, Aug 8, 2019 at 11:00 AM Gagandeep Singh <G.Singh@nxp.com> wrote:
>
> > >HI Thomas,
> > > > > > DPDK currently is supporting maximum 3 hugepage, sizes whereas
> > > > > > system can support more than this e.g.
> > > > > > 64K, 2M, 32M and 1G.
> > > > >
> > > > > You can mention ARM platform here, and that this issue starts with
> > > > > kernel 5.2 (and I would try to mention this in the title as well).
> > > > > This is better than an annotation that will be lost.
> > > > >
> > > > >
> > > > > > Having these four hugepage sizes available to use by DPDK, which is
> > > > > > valid in case of '--in-memory' EAL option or using 4 separate mount
> > > > > > points for each hugepage size;
> > > > > > hugepage_info_init() API reports an error.
> > > > >
> > > > > Can you describe what is the impact from a user point of view rather
> > > > > than mentioning this internal function?
> > > >
> > > > Yes please, we need to understand how much it is critical.
> > > > Should we Cc stable@dpdk.org for backport?
> > > > Should it be merged at the last minute in 19.08?
> > >
> > > VPP usages in-memory option. So, VPP on ARM with kernel 5.2 wont' work
> > without this patch.
> >
> > Do you want to send a v2 with a better explanation?
> >
> > I would suggest to restrict the change to Arm only with an ifdef,
> > in order to limit the risk for this release.
> > We can think about a dynamic hugepage scan in the next release.
> >
> Ok, I will send a v2 with better explanation and will also add an if check to make this change for ARM specific only.

I hope this explanation covers the question I had about when the
change happened in the kernel :-).
Thanks.

-- 
David Marchand