From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-4.sys.kth.se (smtp-4.sys.kth.se [130.237.48.193]) by dpdk.org (Postfix) with ESMTP id 8CF291B537 for ; Tue, 8 Jan 2019 12:30:46 +0100 (CET) Received: from smtp-4.sys.kth.se (localhost.localdomain [127.0.0.1]) by smtp-4.sys.kth.se (Postfix) with ESMTP id 44F8C308; Tue, 8 Jan 2019 12:30:46 +0100 (CET) X-Virus-Scanned: by amavisd-new at kth.se Received: from smtp-4.sys.kth.se ([127.0.0.1]) by smtp-4.sys.kth.se (smtp-4.sys.kth.se [127.0.0.1]) (amavisd-new, port 10024) with LMTP id Jw5JhixehnB7; Tue, 8 Jan 2019 12:30:45 +0100 (CET) Received: from exdb02.ug.kth.se (unknown [192.168.32.112]) by smtp-4.sys.kth.se (Postfix) with ESMTPS id 61C9C449; Tue, 8 Jan 2019 12:30:40 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kth.se; s=default; t=1546947045; bh=e60vLCkAGFlsF0y9dvREGd+mQNd2Q7AzhVlxFOYFGYs=; h=From:To:CC:Subject:Date:References:In-Reply-To; b=Y6mjE1L4mhnr1fOT4iByY6R/mUKIZbDew5R9xnzXo/Qn1JSiHl9WwWdtNVJho1S7c NRBGWnGNSJKFMWwABKkzaSF/0nTBTyTOE4tHUL1LH9uQnOGz6964ZR8MgQWTd5wf9p zc1h9ipkSd1hmFAPInXPucE/5R5IY0OMEcgXAIMI= Received: from exdb06.ug.kth.se (192.168.32.116) by exdb02.ug.kth.se (192.168.32.112) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Tue, 8 Jan 2019 12:30:40 +0100 Received: from exdb05.ug.kth.se (192.168.32.115) by exdb06.ug.kth.se (192.168.32.116) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Tue, 8 Jan 2019 12:30:40 +0100 Received: from exdb05.ug.kth.se ([192.168.32.115]) by exdb05.ug.kth.se ([192.168.32.115]) with mapi id 15.00.1367.000; Tue, 8 Jan 2019 12:30:40 +0100 From: Tom Barbette To: Ferruh Yigit , Shahaf Shuler , "dev@dpdk.org" CC: "bruce.richardson@intel.com" , "john.mcnamara@intel.com" , Thomas Monjalon , Andrew Rybchenko , Yongseok Koh , Alejandro Lucero , Konstantin Ananyev Thread-Topic: [PATCH 1/3] rte_ethdev: Add API function to read dev clock Thread-Index: AQHUmQbEEj1sbwFDeU2CkfY4l17bCqWL1sLQgBBsF4CACRIlCg== Date: Tue, 8 Jan 2019 11:30:39 +0000 Message-ID: <1546947039501.61612@kth.se> References: <3811860b2a7b4bd2be2e9d3fd7de23c0@exdb05.ug.kth.se> , In-Reply-To: Accept-Language: fr-FR, sv-SE, en-US Content-Language: fr-FR X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [212.170.119.194] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH 1/3] rte_ethdev: Add API function to read dev clock X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Jan 2019 11:30:46 -0000 Ferruh Yigit wrote:=0A= > Why timestamp offloading become useless? When timestamp offloading enable= d,=0A= > device fills 'mbuf.timestamp' and you can use it.=0A= But the frequency is unknown, and the reference time neither. So it can be = used only to know that "some time passed" between packets.=0A= =0A= > For your case this timestamp for mlx is device clock and you are adding t= his API=0A= > to be able to convert device clock to real time, this is not something en= ables=0A= > the timestamp offload.=0A= I get your point, but a keyboard is highly required to use a computer. It's= pretty much useless without it. Without this API, the timestamp offload ma= kes no sense. It's a random number generator at best...=0A= =0A= > Technically driver can set the 'mbuf.timestamp' with the real clock right= , if it=0A= > is required? Or this can be defined by a devarg?=0A= I don't think so. Device have no sense of system time. And doing it in the = driver is tricky because it depends on the user needs. Catch-up with NTP up= dates would need a timer and various parameters... Hence we prefer to give = a simple working code, and users may do this if they want.=0A= =0A= =0A= For the other comments it's not my call... I would just underline that time= stamp offload is not usable in the current state, and there is a lot of use= case for monitoring latency-sensitive applications.=0A= =0A= Tom=