On Fri, 9 May 2014, Thomas Gleixner wrote: > > Ok how do I figure out that cpu? I'd rather have a specific cpu that > > never changes. > > I followed the full nohz development only losely, but back then when > all started here at my place with frederic, we had a way to define the > housekeeper cpu. I think we lazily had it hardwired to 0 :)
Yes that would be the easiest and simplest. We dedicate cpu 0 to OS services around here anyways. > That probably changed, but I'm sure there is still a way to define a > housekeeper. And we should simply force the timekeeping on that > housekeeper. That comes with the price, that the housekeeper is not > allowed to go deep idle, but I bet that in HPC scenarios this does not > matter at all simply because the whole machine is under full load. Excellent. Yes. Good. > > > > The vmstat kworker thread checks every 2 seconds if there are vmstat > > updates that need to be folded into the global statistics. This is not > > necessary if the application is running and no OS services are being used. > > Thus we could switch off vmstat updates and avoid taking the processor > > away from the application. > > > > This has also been noted by multiple other people at was brought up at the > > mm summit by others who noted the same issues. > > I understand why you want to get this done by a housekeeper, I just > did not understand why we need this whole move it around business is > required. This came about because of another objection against having it simply fixed to a processor. After all that processor may be disabled etc etc. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
