From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [RFC PATCH v2 2/3] lib: add bitrate statistics
 library
Date: Thu, 27 Oct 2016 18:12:20 -0700
Message-ID: <20161027181220.752e90ea@xeon-e3>
References: <1477616671-9547-1-git-send-email-remy.horton@intel.com>
 <1477616671-9547-3-git-send-email-remy.horton@intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: dev@dpdk.org
To: Remy Horton <remy.horton@intel.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-pf0-f174.google.com (mail-pf0-f174.google.com
 [209.85.192.174]) by dpdk.org (Postfix) with ESMTP id 573FF2904
 for <dev@dpdk.org>; Fri, 28 Oct 2016 03:12:09 +0200 (CEST)
Received: by mail-pf0-f174.google.com with SMTP id e6so26964100pfk.3
 for <dev@dpdk.org>; Thu, 27 Oct 2016 18:12:09 -0700 (PDT)
In-Reply-To: <1477616671-9547-3-git-send-email-remy.horton@intel.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Fri, 28 Oct 2016 09:04:30 +0800
Remy Horton <remy.horton@intel.com> wrote:

> +
> +struct rte_stats_bitrate_s {
> +	uint64_t last_ibytes;
> +	uint64_t last_obytes;
> +	uint64_t peak_ibits;
> +	uint64_t peak_obits;
> +	uint64_t ewma_ibits;
> +	uint64_t ewma_obits;
> +};
> +

Reader/write access of 64 bit values is not safe on 32 bit platforms.
I think you need to add a generation counter (see Linux kernel syncp)
to handle 32 bit architecture. If done correctly, it would be a nop
on 64 bit platforms.