From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756616AbbE2RG7 (ORCPT <rfc822;w@1wt.eu>);
	Fri, 29 May 2015 13:06:59 -0400
Received: from e28smtp09.in.ibm.com ([122.248.162.9]:46772 "EHLO
	e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1756368AbbE2RGv (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Fri, 29 May 2015 13:06:51 -0400
Date: Fri, 29 May 2015 22:36:00 +0530
From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Balbir Singh <bsingharora@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, srikar@linux.vnet.ibm.com
Subject: Re: [PATCH] proc/schedstat: Expose /proc/<pid>/schedstat if delay
 accounting is enabled
Message-ID: <20150529170600.GF17421@naverao1-tp.ibm.com>
References: <1432537954-26665-1-git-send-email-naveen.n.rao@linux.vnet.ibm.com>
 <CAKTCnzm5A6n=jvskHqUmpdq7yynzKqwuVFJL-ia=3PmgDeBV-w@mail.gmail.com>
 <20150529061620.GA17421@naverao1-tp.ibm.com>
 <20150529080424.GA27235@gmail.com>
 <20150529085504.GD17421@naverao1-tp.ibm.com>
 <20150529091837.GA30451@gmail.com>
 <20150529094547.GE17421@naverao1-tp.ibm.com>
 <20150529095435.GA30949@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20150529095435.GA30949@gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
X-TM-AS-MML: disable
X-Content-Scanned: Fidelis XPS MAILER
x-cbid: 15052917-0033-0000-0000-0000060629EB
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 2015/05/29 11:54AM, Ingo Molnar wrote:
> 
> > > So all this should really be cleaned up:
> > > 
> > > include/linux/sched.h:#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
> > > include/linux/sched.h:#endif /* defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) */
> > > include/linux/sched.h:#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
> > > kernel/sched/core.c:#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
> > > kernel/sched/stats.h:#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
> > > kernel/sched/stats.h:#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
> > > 
> > > by introducing an intermediate Kconfig variable, named CONFIG_SCHED_INFO or so, 
> > > and selected by both SCHEDSTATS and TASK_DELAY_ACCT.
> > > 
> > > Please make it two patches: the first one adds CONFIG_SCHED_INFO and cleans up the 
> > > code to use it, the second one uses it for the procps change.
> > 
> > Sure, will do.
> > 
> > On a related note, even though sum_exec_runtime is available unconditionally, I 
> > dump all zeroes in my patch if !sched_info_on() to make it clear that some of 
> > the fields are not available. Is this ok or should be display sum_exec_runtime 
> > regardless of sched_info?
> 
> So I'd suggest printing -1 for non-available fields, that should be unambigous 
> enough and makes it also possible to write out 0 in some cases.

Per Documentation/scheduler/sched-stats.txt (and the linked latency.c 
there), user-space seems to be expecting unsigned values here. Would 
displaying -1 here be ok?


Thanks,
Naveen