From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
To: Bruce Richardson <bruce.richardson@intel.com>,
"Akhil.goyal@nxp.com" <akhil.goyal@nxp.com>,
Ray Kinsella <mdr@ashroe.eu>
Cc: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"Gujjar, Abhinandan S" <abhinandan.gujjar@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"Doherty, Declan" <declan.doherty@intel.com>,
"techboard@dpdk.org" <techboard@dpdk.org>,
"Vangati, Narender" <narender.vangati@intel.com>,
"jerinj@marvell.com" <jerinj@marvell.com>, nd <nd@arm.com>
Subject: Re: [dpdk-dev] [dpdk-techboard] [v4 1/3] cryptodev: support enqueue callback functions
Date: Wed, 28 Oct 2020 15:22:06 +0000 [thread overview]
Message-ID: <DBAPR08MB58147711C02EB901451D2AE598170@DBAPR08MB5814.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <20201028151130.GD1634@bricha3-MOBL.ger.corp.intel.com>
+ Ray for ABI
<snip>
>
> On Wed, Oct 28, 2020 at 02:28:43PM +0000, Akhil Goyal wrote:
> >
> > Hi Konstantin,
> >
> > > > > Hi Tech board members,
> > > > >
> > > > > I have a doubt about the ABI breakage in below addition of field.
> > > > > Could you please comment.
> > > > >
> > > > > > /** The data structure associated with each crypto device. */
> > > > > > struct rte_cryptodev {
> > > > > > dequeue_pkt_burst_t dequeue_burst; @@ -867,6 +922,10
> @@
> > > > > > struct rte_cryptodev {
> > > > > > __extension__
> > > > > > uint8_t attached : 1;
> > > > > > /**< Flag indicating the device is attached */
> > > > > > +
> > > > > > + struct rte_cryptodev_enq_cb_rcu *enq_cbs;
> > > > > > + /**< User application callback for pre enqueue processing */
> > > > > > +
> > > > > > } __rte_cache_aligned;
> > > > >
> > > > > Here rte_cryptodevs is defined in stable API list in map file
> > > > > which is a pointer To all rte_cryptodev and the above change is
> > > > > changing the size of the
> > > structure.
> > >
> > > While this patch adds new fields into rte_cryptodev structure, it
> > > doesn't change the size of it.
> > > struct rte_cryptodev is cache line aligned, so it's current size:
> > > 128B for 64-bit systems, and 64B(/128B) for 32-bit systems.
> > > So for 64-bit we have 47B implicitly reserved, and for 32-bit we
> > > have 19B reserved.
> > > That's enough to add two pointers without changing size of this struct.
> > >
> >
> > The structure is cache aligned, and if the cache line size in 32Byte
> > and the compilation is done on 64bit machine, then we will be left
> > with 15Bytes which is not sufficient for 2 pointers.
> > Do we have such systems? Am I missing something?
> >
>
> I don't think we support any such systems, so unless someone can point out
> a specific case where we need to support 32-byte CLs, I'd tend towards
> ignoring this as a non-issue.
Agree. I have not come across 32B cache line.
>
> > The reason I brought this into techboard is to have a consensus on
> > such change As rte_cryptodev is a very popular and stable structure.
> > Any changes to it may Have impacts which one person cannot judge all use
> cases.
> >
>
> Haven't been tracking this discussion much, but from what I read here, this
> doesn't look like an ABI break and should be ok.
If we are filling the holes in the cache line with new fields, it should not be an ABI break.
>
> Regards,
> /Bruce
next prev parent reply other threads:[~2020-10-28 15:22 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-25 9:44 [dpdk-dev] [v4 0/3] support enqueue callbacks on cryptodev Abhinandan Gujjar
2020-10-25 9:44 ` [dpdk-dev] [v4 1/3] cryptodev: support enqueue callback functions Abhinandan Gujjar
2020-10-27 12:47 ` Ananyev, Konstantin
2020-10-27 17:16 ` Gujjar, Abhinandan S
2020-10-27 17:20 ` Ananyev, Konstantin
2020-10-27 17:22 ` Gujjar, Abhinandan S
2020-10-27 18:19 ` Akhil Goyal
2020-10-27 19:16 ` Gujjar, Abhinandan S
2020-10-27 19:26 ` Akhil Goyal
2020-10-27 19:41 ` Gujjar, Abhinandan S
2020-10-27 18:28 ` Akhil Goyal
2020-10-28 8:20 ` Gujjar, Abhinandan S
2020-10-28 12:55 ` Ananyev, Konstantin
2020-10-28 14:28 ` Akhil Goyal
2020-10-28 14:52 ` Ananyev, Konstantin
2020-10-28 15:11 ` [dpdk-dev] [dpdk-techboard] " Bruce Richardson
2020-10-28 15:22 ` Honnappa Nagarahalli [this message]
2020-10-29 13:52 ` Gujjar, Abhinandan S
2020-10-29 14:00 ` Akhil Goyal
2020-10-30 4:24 ` Gujjar, Abhinandan S
2020-10-30 17:18 ` Gujjar, Abhinandan S
2020-10-29 14:26 ` Kinsella, Ray
2020-10-25 9:44 ` [dpdk-dev] [v4 2/3] test: add testcase for crypto enqueue callback Abhinandan Gujjar
2020-10-25 9:44 ` [dpdk-dev] [v4 3/3] doc: add enqueue callback APIs Abhinandan Gujjar
2020-10-26 19:08 ` Akhil Goyal
2020-10-27 3:52 ` Gujjar, Abhinandan S
2020-10-27 12:51 ` Ananyev, Konstantin
2020-10-27 17:17 ` Gujjar, Abhinandan S
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