From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <dev-bounces@dpdk.org>
Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124])
	by inbox.dpdk.org (Postfix) with ESMTP id B5B1F41BBD;
	Fri,  3 Feb 2023 15:25:08 +0100 (CET)
Received: from mails.dpdk.org (localhost [127.0.0.1])
	by mails.dpdk.org (Postfix) with ESMTP id 434F34067B;
	Fri,  3 Feb 2023 15:25:08 +0100 (CET)
Received: from smartserver.smartsharesystems.com
 (smartserver.smartsharesystems.com [77.243.40.215])
 by mails.dpdk.org (Postfix) with ESMTP id 83E794021E
 for <dev@dpdk.org>; Fri,  3 Feb 2023 15:25:07 +0100 (CET)
X-MimeOLE: Produced By Microsoft Exchange V6.5
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Subject: RE: [PATCH] eal: introduce atomics abstraction
Date: Fri, 3 Feb 2023 15:25:05 +0100
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35D876FA@smartserver.smartshare.dk>
In-Reply-To: <Y90SleioKJxk6QqN@bricha3-MOBL.ger.corp.intel.com>
X-MS-Has-Attach: 
X-MS-TNEF-Correlator: 
Thread-Topic: [PATCH] eal: introduce atomics abstraction
Thread-Index: Adk312GRhZr/TXmPQku48z1OSp3b0QAAdAdA
References: <1673558785-24992-1-git-send-email-roretzla@linux.microsoft.com>
 <1673558785-24992-2-git-send-email-roretzla@linux.microsoft.com>
 <1844463.CQOukoFCf9@thomas>
 <DBAPR08MB58149E9137F83A338B2D6B2198D19@DBAPR08MB5814.eurprd08.prod.outlook.com>
 <20230201214111.GA30564@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
 <98CBD80474FA8B44BF855DF32C47DC35D876EE@smartserver.smartshare.dk>
 <20230202190023.GA32597@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
 <98CBD80474FA8B44BF855DF32C47DC35D876F7@smartserver.smartshare.dk>
 <Y90SleioKJxk6QqN@bricha3-MOBL.ger.corp.intel.com>
From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Bruce Richardson" <bruce.richardson@intel.com>
Cc: "Tyler Retzlaff" <roretzla@linux.microsoft.com>,
 "Honnappa Nagarahalli" <Honnappa.Nagarahalli@arm.com>,
 <thomas@monjalon.net>, <dev@dpdk.org>, <david.marchand@redhat.com>,
 <jerinj@marvell.com>, <konstantin.ananyev@huawei.com>,
 <ferruh.yigit@amd.com>, "nd" <nd@arm.com>
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <https://mails.dpdk.org/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://mails.dpdk.org/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <https://mails.dpdk.org/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org

> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> Sent: Friday, 3 February 2023 14.57
>=20
> Having read through the whole thread a second time, I am starting to
> realise how complex a problem this could be. From what I read, I would
> tend
> towards the opinion that we shouldn't provide any atomics in DPDK at
> all,
> and just rely on the C standard ones.

Yes, but atomics were only standardized for C with C11. So that is the =
problem - and a good reason for pushing for C11.

Before C11, there were only compiler specific intrinsics.

> The main complication in any
> solution
> I suspect is going to be the use of atomics in static inline functions
> we
> have in our header files.

Not only that.

If we consider atomic variables (and the type of such variables) private =
to DPDK, we would need to provide public functions to manipulate those =
atomic variables. If not, the application will be unable to interact =
with them.

And if we expose such functions, why not also make the DPDK atomic type =
itself public? In other words, expose a DPDK API for atomics, such as =
Tyler's.

(And as I mentioned on the techboard meeting, I think atomic operations =
should be available in inline code, for performance reasons.)

-Morten