Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752084AbbKYRc0 (ORCPT ); Wed, 25 Nov 2015 12:32:26 -0500 Received: from mail-pa0-f42.google.com ([209.85.220.42]:34167 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211AbbKYRcR (ORCPT ); Wed, 25 Nov 2015 12:32:17 -0500 Message-ID: <5655F09E.1060004@linaro.org> Date: Wed, 25 Nov 2015 09:32:14 -0800 From: "Shi, Yang" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Nicolas Pitre , Jon Masters CC: Will.Deacon@arm.com, Catalin.Marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linaro-kernel@lists.linaro.org Subject: Re: [PATCH] arm64: restore bogomips information in /proc/cpuinfo References: <1447870505-19319-1-git-send-email-yang.shi@linaro.org> <56554AE9.5070901@jonmasters.org> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2057 Lines: 51 On 11/25/2015 7:16 AM, Nicolas Pitre wrote: > On Wed, 25 Nov 2015, Jon Masters wrote: > >> On 11/18/15, 1:15 PM, Yang Shi wrote: >> >>> As what Pavel Machek reported [1], some userspace applications depend on >>> bogomips showed by /proc/cpuinfo. >>> >>> Although there is much less legacy impact on aarch64 than arm, but it does >>> break libvirt. >>> >>> Basically, this patch reverts commit >>> 326b16db9f69fd0d279be873c6c00f88c0a4aad5 >>> ("arm64: delay: don't bother reporting bogomips in /proc/cpuinfo"), but with >>> some tweak due to context change. >> >> On a total tangent, it would be ideal to (eventually) have something reported >> in /proc/cpuinfo or dmesg during boot that does "accurately" map back to the >> underlying core frequency (as opposed to the generic timer frequency). I have >> seen almost countless silly situations in the industry (external to my own >> organization) in which someone has taken a $VENDOR_X reference system that >> they're not supposed to run benchmarks on, and they've done it anyway. But >> usually on some silicon that's clocked multiples under what production would >> be. Then silly rumors about performance get around because nobody can do >> simple arithmetic and notice that they ought to have at least divided by some >> factor. > > Be my guest my friend. > > According to the common wisdom, the bogomips reporting is completely > senseless at this point and no one should expect anything useful from > it. Therefore I attempted to rehabilitate some meaning into it given > that we just can't get rid of it either and it continues to cause > dammage. You certainly saw where that has led me. Or we may create a new one, i.e. "cpu MHz" like x86? Then we keep both in cpuinfo so that the userspace could adopt it gradually? Thanks, Yang > > > Nicolas > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/