From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: 64-bit net_device_stats Date: Thu, 03 Jun 2010 15:51:07 +0100 Message-ID: <1275576667.2106.11.camel@achroite.uk.solarflarecom.com> References: <1275514469.2115.70.camel@achroite.uk.solarflarecom.com> <20100602145912.56ef62c2@nehalam> <201006030138.17668.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , David Miller , junchangwang@gmail.com, romieu@fr.zoreil.com, netdev@vger.kernel.org To: Arnd Bergmann Return-path: Received: from mail.solarflare.com ([216.237.3.220]:53968 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755139Ab0FCOvL (ORCPT ); Thu, 3 Jun 2010 10:51:11 -0400 In-Reply-To: <201006030138.17668.arnd@arndb.de> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2010-06-03 at 01:38 +0200, Arnd Bergmann wrote: > On Wednesday 02 June 2010 23:59:12 Stephen Hemminger wrote: > > On Wed, 02 Jun 2010 22:34:29 +0100 > > Ben Hutchings wrote: > > > > > Changing the counter types to u64 for 32-bit architectures would remove > > > atomicity and expose half-updated counters to userland. Changing the > > > driver interface significantly so that atomicity is not needed would > > > require changes to hundreds of drivers. > > > > Another big issue is maintaining ABI compatibility for /proc and ioctl > > interfaces. So bigger values would only be available through netlink, > > and most applications using counters don't use netlink. > > Doesn't the /proc interface already allow 64 bit values in case of > 64 bit hosts running the same 32 bit user space? Yes. And the most widely used consumer of /proc/net/dev, ifconfig, already parses them as 64-bit values. > For the ioctl interfaces, we can of course introduce additional > ioctl commands that always deal with 64 bit values, many other > subsystems have been extended in similar ways. [...] Are there any ioctl interfaces to net_device_stats? I didn't spot any. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.