From: Bruce Richardson <bruce.richardson@intel.com>
To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
Ali Alnubani <alialnu@nvidia.com>, "dev@dpdk.org" <dev@dpdk.org>,
Asaf Penso <asafp@nvidia.com>,
"david.marchand@redhat.com" <david.marchand@redhat.com>,
"arybchenko@solarflare.com" <arybchenko@solarflare.com>,
"ferruh.yigit@intel.com" <ferruh.yigit@intel.com>,
"honnappa.nagarahalli@arm.com" <honnappa.nagarahalli@arm.com>
Subject: Re: [dpdk-dev] [EXT] Re: performance degradation with fpic
Date: Fri, 16 Oct 2020 09:29:51 +0100 [thread overview]
Message-ID: <20201016082951.GA1008@bricha3-MOBL.ger.corp.intel.com> (raw)
In-Reply-To: <BYAPR18MB242486142E1889AE1E566991C8020@BYAPR18MB2424.namprd18.prod.outlook.com>
On Thu, Oct 15, 2020 at 05:28:10PM +0000, Jerin Jacob Kollanukkaran wrote:
> > -----Original Message-----
> > From: Thomas Monjalon <thomas@monjalon.net>
> > Sent: Thursday, October 15, 2020 10:45 PM
> > To: Ali Alnubani <alialnu@nvidia.com>; Bruce Richardson
> > <bruce.richardson@intel.com>
> > Cc: dev@dpdk.org; Asaf Penso <asafp@nvidia.com>;
> > david.marchand@redhat.com; arybchenko@solarflare.com;
> > ferruh.yigit@intel.com; honnappa.nagarahalli@arm.com; Jerin Jacob
> > Kollanukkaran <jerinj@marvell.com>
> > Subject: [EXT] Re: performance degradation with fpic
> >
> > External Email
> >
> > ----------------------------------------------------------------------
> > 15/10/2020 19:08, Bruce Richardson:
> > > On Thu, Oct 15, 2020 at 04:00:44PM +0000, Ali Alnubani wrote:
> > > > We have been seeing in some cases that the DPDK forwarding
> > performance
> > > > is up to 9% lower when DPDK is built as static with meson compared to a
> > > > build with makefiles.
> > > >
> > > > The same degradation can be reproduced with makefiles on older DPDK
> > > > releases when building with EXTAR_CFLAGS set to “-fPIC”, it can also be
> > > > resolved in meson when passing “pic: false” to meson’s static_library
> > > > call (more tweaking needs to be done to prevent building shared
> > > > libraries because this change breaks them).
> > [...]
> > > > Should we disable PIC in static builds?
> > >
> > > thanks for reporting, though it's strange that you see such a big impact.
> > > In my previous tests with i40e driver I never noticed a difference
> > > between make and meson builds, and I and some others here have been
> > > using meson builds for any performance work for over a year now. That
> > > being said let me reverify what I see on my end.
> > >
> > > In terms of solutions, disabling the -fPIC flag globally implies that
> > > we can no longer build static and shared libs from the same sources,
> > > so we would need to revert to doing either a static or a shared
> > > library build but not both. If the issue is limited to only some
> > > drivers or some cases, we can perhaps add in a build option to have
> > > no-fpic-static builds, to be used in a cases where it is problematic.
>
> We have seen this issue earlier. Our issue was, meson, getting more performance
> Than make build system(Based on different changeset). Initially we suspected fpic
> is playing role. Based on our understanding, It not is fpic issue per say, it is more
> of text section code alignment change was creating the issue.
> Typically it happen with very "fine" grained, prefetches in Rx and Tx routines, then
> All timing will get changed by radical change to text section by fpic.
>
Out of interest, what range of performance difference did you see, because
the 9% reported is fairly massive, well beyond anything I would expect from
such a change?
next prev parent reply other threads:[~2020-10-16 8:30 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 16:00 [dpdk-dev] " Ali Alnubani
2020-10-15 17:08 ` Bruce Richardson
2020-10-15 17:14 ` Thomas Monjalon
2020-10-15 17:28 ` [dpdk-dev] [EXT] " Jerin Jacob Kollanukkaran
2020-10-16 8:29 ` Bruce Richardson [this message]
2020-10-16 8:39 ` Jerin Jacob
2020-10-15 21:44 ` [dpdk-dev] " Stephen Hemminger
2020-10-16 8:35 ` Bruce Richardson
2020-10-16 9:59 ` Bruce Richardson
2020-10-19 11:47 ` Ali Alnubani
2020-10-19 13:01 ` Bruce Richardson
2020-10-22 13:17 ` Ali Alnubani
2020-10-22 13:57 ` Bruce Richardson
2020-10-22 14:16 ` Ali Alnubani
2020-11-02 10:40 ` Ali Alnubani
2020-11-02 11:01 ` Luca Boccassi
2020-11-02 15:00 ` Bruce Richardson
2020-11-03 10:18 ` Thomas Monjalon
2020-11-03 10:45 ` Luca Boccassi
2020-11-03 11:23 ` Bruce Richardson
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