From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3t8Ldx5LXLzDt31 for ; Thu, 3 Nov 2016 08:22:13 +1100 (AEDT) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uA2LJ47I027171 for ; Wed, 2 Nov 2016 17:22:11 -0400 Received: from e06smtp11.uk.ibm.com (e06smtp11.uk.ibm.com [195.75.94.107]) by mx0b-001b2d01.pphosted.com with ESMTP id 26fmraqbr9-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 02 Nov 2016 17:22:10 -0400 Received: from localhost by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 2 Nov 2016 21:22:09 -0000 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id A53DD1B0805F for ; Wed, 2 Nov 2016 21:24:17 +0000 (GMT) Received: from d06av09.portsmouth.uk.ibm.com (d06av09.portsmouth.uk.ibm.com [9.149.37.250]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id uA2LM7UE16056676 for ; Wed, 2 Nov 2016 21:22:07 GMT Received: from d06av09.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av09.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id uA2LM75s001149 for ; Wed, 2 Nov 2016 15:22:07 -0600 Date: Wed, 2 Nov 2016 22:22:00 +0100 From: Martin Schwidefsky To: Stanislaw Gruszka Cc: Christian Borntraeger , linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Frederic Weisbecker , Paul Mackerras , Benjamin Herrenschmidt , Michael Neuling , linuxppc-dev@lists.ozlabs.org, Heiko Carstens , linux-s390@vger.kernel.org Subject: Re: [PATCH 3/4] cputime/powerpc/s390: make scaled cputime arch specific In-Reply-To: <20161102093820.GC2604@redhat.com> References: <1477917389-11341-1-git-send-email-sgruszka@redhat.com> <1477917389-11341-4-git-send-email-sgruszka@redhat.com> <9ad862f2-5665-08d6-4e5d-793637efcb66@de.ibm.com> <20161102093820.GC2604@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Message-Id: <20161102222200.14bc8cb6@mschwide> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2 Nov 2016 10:38:20 +0100 Stanislaw Gruszka wrote: > On Wed, Nov 02, 2016 at 10:11:22AM +0100, Christian Borntraeger wrote: > > On 10/31/2016 01:36 PM, Stanislaw Gruszka wrote: > > > Only s390 and powerpc have hardware facilities allowing to measure > > > cputimes scaled by frequency. On all other architectures > > > utimescaled/stimescaled are equal to utime/stime (however they are > > > accounted separately). > > > > > > Patch remove {u,s}timescaled accounting on all architectures except > > > powerpc and s390, where those values are explicitly accounted on proper > > > places. > > > > If we remove it everywhere else (and assuming that there are no users then) > > I aks myself if we should remove this as well from s390. > > There is one user of scaled cputimes values, it is taskstats (to users > space are exported ac_utimescaled, ac_stimescaled and > cpu_scaled_run_real_total which is calculated based on scaled times). > However on other than powerpc and s390 architectures scaled times are > equal to normal times (this is also true for older powerpc's without > SPURR/PURR registers). The taskstats interface is the only user of the scaled cputime that I am aware of. It is hard to say how valuable the information is. Without the scaled number in the taskstats inferface you have no means to detect if your workload has been affected by a another SMT thread running on the same core. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.