On 02/12/2012 01:12 PM, gene heskett wrote: >> Gene, >> >> About tracking that occasional blip on the isolcpu, have you used atop? >> Consider it a "top" on steroids. It shows processes running much like >> top, but also displays what cpu they are running on. Here's the atop >> web site: http://www.atoptool.nl >> >> Click on the screen shots and take a peek at what atop has over the top >> utility. I use it at work. >> >> Mark >> >> > This prompted me to do a little more experimenting between running it as > lcnc, which is a script that does the taskset, and running it as linuxcnc > which does not. Then either way atop did not detect enough activity on the > 2nd cpu to bother listing it more than 5% of the time. In that regard, > htop, which displays each cpu it is configured for, full time as a slider > in the upper area of its screen. To me, htop is the better utility, but > then I am used to it and have been using it for years on this box full > time. > > ksysguard OTOH used for the rest of this testing, showed a higher cpu usage > overall for both cpu's and cpu001 was consistently in the 50-60% range when > taskset was in effect, and about a 20% less total when it was not, only > with possibly an 8% peak for #1 while it was running a 20 minute program > with the motors off. > > Which of these two monitors utils is correct, I'll have to plead the 5th on > as I don't have a clue. > > Then I thought I'd see how fast I can run the base thread, starting to hit > realtime delays when taskset was used at about 17 microseconds, and pretty > consistently at 14 microseconds, and when taskset was not used, I could go > down another microsecond, perhaps 2. Without taskset, and at 19 > microseconds, it has now run that 20 minute program 3 times without a delay > warning thrown. > > This of course is without the local and slower gfx delays that relatively > poor intel gfx chip will cause when it is using its own X to display the > axis output. Hooking up my lappy, and ssh-ing into it so as to use the > laptops gfx, probably wouldn't be quite that advantageous as its an ati gfx > chipset and only a 1.4Ghz 'turion', but I'd think, until I observe > otherwise, that what I'd see would be laggy gfx if the miss-match was too > great. > > I guess what I'm saying is that in the overall scheme, using taskset isn't > the magic twanger I thought it might be. The gfx in use, from this testing > would seem to have the more noticeable effect. I will, very occasionally > hit a realtime delay when running on its own x server& local screen with a > 20 microsecond base thread when using taskset. Konversation is running, > but firefox is not, kcalc and update_manager are but neither of the last > are using detectable cpu. > > When I installed atop, it started an atop daemon, but I have no clue if it > is actually active and collecting data when the display isn't running, in > any event I just now used htop to run it down& send it a quit signal just > in case. > > htop, FWIW, is showing cpu1 at around .5% so it must be using the same > mechanism as atop to collect the data. As this HAS to be a bit intrusive, > its possible it might cost a microsecond in base thread time to actually > collect the data. I don't normally run it, or ksysguard, on that box since > the gfx for ksysguard would have to impinge on the rest of the system. > > Conclusion? Forget taskset, and export the display to a remote server for > best realtime performance. I believe that is the same conclusion some of > you have reached. However, the improvement wouldn't seem to warrant the > sheckels to buy another of those boxes and a display, territory of $375 > additional cost, although that box could probably boot from a usb key and > wouldn't need a dvd writer, bringing that back down to perhaps $300. Still > not worth the minuscule improvement IMO. > > Thanks Mark. > > Cheers, Gene > Gene,
Yeah, atop does run as a daemon collecting info in the background. If you crank up atop on the command line with the -s switch, you get a neat screen which shows what CPU the process is running on. On my Ubuntu 11.10 with a quad core, I see processes occasionally running on all four. Mark ------------------------------------------------------------------------------ Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
