From: Amit Prakash Shukla <amitprakashs@marvell.com>
To: Thomas Monjalon <thomas@monjalon.net>,
Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>,
Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
Jerin Jacob Kollanukkaran <jerinj@marvell.com>,
"david.marchand@redhat.com" <david.marchand@redhat.com>,
"bruce.richardson@intel.com" <bruce.richardson@intel.com>,
"ferruh.yigit@amd.com" <ferruh.yigit@amd.com>
Subject: RE: [EXT] Re: [PATCH] ring: compilation fix with GCC-12
Date: Fri, 13 Jan 2023 12:39:07 +0000 [thread overview]
Message-ID: <PH0PR18MB516748B30A72EFAA2F00E8B7C8C29@PH0PR18MB5167.namprd18.prod.outlook.com> (raw)
In-Reply-To: <837071028.0ifERbkFSE@thomas>
Hi Thomas,
> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Friday, January 13, 2023 3:12 AM
> To: Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>; Honnappa
> Nagarahalli <Honnappa.Nagarahalli@arm.com>; Amit Prakash Shukla
> <amitprakashs@marvell.com>
> Cc: dev@dpdk.org; Jerin Jacob Kollanukkaran <jerinj@marvell.com>;
> david.marchand@redhat.com; bruce.richardson@intel.com;
> ferruh.yigit@amd.com
> Subject: Re: [EXT] Re: [PATCH] ring: compilation fix with GCC-12
>
> 23/08/2022 11:38, Amit Prakash Shukla:
> > From: Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>
> > > 06/08/2022 19:35, Honnappa Nagarahalli пишет:
> > > >> Replacing memcpy with rte_memcpy fixes the GCC-12 compilation
> issue.
> > > >
> > > > Any reason why this replacement fixes the problem?
> > > > Do you have any performance numbers with this change?
> > > >
> > > >> Also it would be better to change to rte_memcpy as the function
> > > >> is called in fastpath.
> > > >
> > > > On Arm platforms, memcpy in the later versions has the best
> performance.
> > >
> > > I agree with Honnappa, it is better to keep memcpy() here.
> > > Actually what is strange - why it ends up in
> > > __rte_ring_dequeue_elems_128() at all?
> > > Inside rxa_intr_ring_dequeue() we clearly doing: rte_ring_dequeue(),
> > > which should boil down to ___rte_ring_dequeue_elems_64().
> > > it should go to __rte_ring_dequeue_elems_128() at all.
> >
> > I agree. After having close look and doing few experiments, ideally it
> > should not be going to __rte_ring_dequeue_elems_128().
> > Sizeof(in call of rte_ring_enqueue_elem) gets evaluated at compile
> > time which in this case it is evaluated to 8 bytes so
> > __rte_ring_dequeue_elems_128() shall not be in the path. Looks like more
> of a gcc-12 bug.?
> >
> > > Another q - is this warning happens only on arm platforms?
> >
> > Warning is observed on x86 with build type as debug.
> > "meson --werror --buildtype=debug build"
>
> I confirm the compilation issue on x86 with GCC 12 in a debug build.
>
> We need to find a workaround.
> Is it reported to GCC already?
>
I found an old gcc bug reporting similar issue. This bug seems to be re-opened recently in Dec-2022. Not sure if it is reopened specifically for gcc-12.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89689
Kevin has push a work around for DPDK-21.11.3.
https://git.dpdk.org/dpdk-stable/commit/?h=21.11&id=e1d728588dc73af9ed60cc0074d51a7f24b2ba60
next prev parent reply other threads:[~2023-01-13 12:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-05 9:03 Amit Prakash Shukla
2022-08-05 15:37 ` Stephen Hemminger
2022-08-06 18:35 ` Honnappa Nagarahalli
2022-08-07 12:26 ` Konstantin Ananyev
2022-08-23 9:38 ` [EXT] " Amit Prakash Shukla
2022-08-23 9:41 ` Amit Prakash Shukla
2023-01-12 21:41 ` Thomas Monjalon
2023-01-13 12:39 ` Amit Prakash Shukla [this message]
2023-01-13 13:11 ` Thomas Monjalon
2023-02-13 1:48 ` Konstantin Ananyev
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