Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1753692AbcKUJt3 (ORCPT <rfc822;w@1wt.eu>);
        Mon, 21 Nov 2016 04:49:29 -0500
Received: from mail-wj0-f195.google.com ([209.85.210.195]:35661 "EHLO
        mail-wj0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752870AbcKUJt2 (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 21 Nov 2016 04:49:28 -0500
Date: Mon, 21 Nov 2016 10:49:23 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>, Tony Luck <tony.luck@intel.com>,
        Wanpeng Li <wanpeng.li@hotmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Paul Mackerras <paulus@samba.org>, Fenghua Yu <fenghua.yu@intel.com>,
        Rik van Riel <riel@redhat.com>,
        Stanislaw Gruszka <sgruszka@redhat.com>
Subject: Re: [PATCH 00/36] cputime: Convert core use of cputime_t to nsecs
Message-ID: <20161121094923.GA22910@gmail.com>
References: <1479406123-24785-1-git-send-email-fweisbec@gmail.com>
 <20161118130846.7da515cc@mschwide>
 <20161118144700.GA31560@lerouge>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20161118144700.GA31560@lerouge>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 913
Lines: 23


* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> > But I am still not happy about the approach. What is the compelling reason for 
> > this change except for the "but it looks ugly"?
> 
> The diffstat (600 lines removed). Also the fact that we have all these 
> workarounds in the core code just for the special case of 1 arch (s390) and a 
> half (powerpc with CONFIG_VIRT_CPU_ACCOUNTING_NATIVE).
> 
> I'd much rather have all that complexity moved in a vtime_native.c shared by 
> s390 and powerpc that takes care of proper accumulation in cputime_t and flushes 
> that on ticks in nsecs rather than having all these cputime_t game all over the 
> kernel.

I agree - we really want to concentrate complexity in such a fashion and generally 
standardize on nanosecs, and the diffstat of the patchset is really nice.

The patchset obviously has to build (and work!) on s390/powerpc properly.

Thanks,

	Ingo