From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Michael Neuling To: balbir@linux.vnet.ibm.com Subject: Re: [PATCH 1/2] Add scaled time to taskstats based process accounting In-reply-to: <46C805B0.1000300@linux.vnet.ibm.com> References: <20070816070922.37B5370074@localhost.localdomain> <46C3FC41.4000609@linux.vnet.ibm.com> <19998.1187312981@neuling.org> <20070817115951.e1368a7d.akpm@linux-foundation.org> <46C805B0.1000300@linux.vnet.ibm.com> Date: Sun, 19 Aug 2007 23:12:07 +1000 Message-ID: <18727.1187529127@neuling.org> Cc: Benjamin@ozlabs.org, Jay Lan , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Paul Mackerras , Andrew Morton List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , In message <46C805B0.1000300@linux.vnet.ibm.com> you wrote: > 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 ... or even #ifdef TASKSTATS > 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 >