On Thu, 2013-03-07 at 14:11 +1100, Paul Mackerras wrote: > On Wed, Mar 06, 2013 at 09:52:16PM -0300, Marcelo Tosatti wrote: > > On Wed, Mar 06, 2013 at 10:29:12AM -0600, Michael Wolf wrote: > > > I looked at doing that once but was told that I was changing the > > > interface in an unacceptable way, because now I was not reporting all of > > > the elapsed time. I agree it would make things simpler. > > > > Pointer to that claim, please? > > Back in about 2004 or 2005 or so I was looking at changing how user > and system times were calculated (in the context of trying to find a > better way to report resources used by a thread in an SMT processor). > I found that utilities such as top expected the deltas in the > /proc/stat numbers to add up to elapsed time, and would report strange > and inconsistent results if that wasn't the case. Unfortunately at > this distance I don't recall the exact details. I don't know whether > the expectation that the deltas in the /proc/stat numbers over a > period of time add up to the elapsed real time is documented anywhere, > but I wouldn't be at all surprised if some programs depend on it, so > it's better to maintain that property. I will have to look at this again. When looking at the cpu data where steal time is reported there isn't a problem today. I will have to run it and see if there is anything incorrect with the time being reported for the individual processes. My real concern here was that in changing the /proc/stat interface am I going to mess private tools that look at that information. When I've looked at vmstat and top they report the cpu information fine, but I may end up creating problems for home grown scripts and tools. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
