Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754055AbXHSI5U (ORCPT ); Sun, 19 Aug 2007 04:57:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752100AbXHSI5F (ORCPT ); Sun, 19 Aug 2007 04:57:05 -0400 Received: from ausmtp06.au.ibm.com ([202.81.18.155]:51875 "EHLO ausmtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751730AbXHSI4c (ORCPT ); Sun, 19 Aug 2007 04:56:32 -0400 Message-ID: <46C805B0.1000300@linux.vnet.ibm.com> Date: Sun, 19 Aug 2007 14:26:16 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com Organization: IBM User-Agent: Thunderbird 1.5.0.12 (X11/20070604) MIME-Version: 1.0 To: Andrew Morton CC: Michael Neuling , Jay Lan , Benjamin@ozlabs.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Paul Mackerras Subject: Re: [PATCH 1/2] Add scaled time to taskstats based process accounting References: <20070816070922.37B5370074@localhost.localdomain> <46C3FC41.4000609@linux.vnet.ibm.com> <19998.1187312981@neuling.org> <20070817115951.e1368a7d.akpm@linux-foundation.org> In-Reply-To: <20070817115951.e1368a7d.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1621 Lines: 47 Andrew Morton wrote: >> >> unsigned int rt_priority; >> - cputime_t utime, stime; >> + cputime_t utime, stime, utimescaled, stimescaled; > > Adding 8 or 16 bytes to the task_struct for all architectures for something > which only powerpc uses? > > Is there any prospect that other CPUs can use this? > Hi, Andrew, There is definitely the prospect for other architectures to use this feature x86 provides the APERF and MPERF model specific registers. The ratio of APERF to MPERF gives the current scaled load on the system (acpi-cpufreq, get_measured_perf()) I have been looking at exploiting this functionality for x-series, but ran into a problem; as per the specification, APERF and MPERF are to be reset to 0 upon reading them. As a result, I am still figuring out a good way to share the data amongst the ondemand governor and utimescaled statistics. I think for now, we can 1. Put utimescaled and stimescaled under an #ifdef for ARCH_POWERPC 2. Add utimescaled and stimescaled and add a big fat comment stating that work for other architectures is on it's way. In either case, I think the functionality is useful and can be exploited by other architectures. The powerpc port is complete and I think the implementation would provide a good reference for other implementations to follow. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL - 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/