On Tue, Oct 21, 2014 at 03:08:32PM +0200, Stephane Eranian wrote: > On Tue, Oct 21, 2014 at 3:03 PM, Peter Zijlstra <[email protected]> wrote: > > On Tue, Oct 21, 2014 at 02:28:06PM +0200, Stephane Eranian wrote: > >> Peter, > >> > >> On Tue, Oct 21, 2014 at 1:25 PM, Peter Zijlstra <[email protected]> > >> wrote: > >> > > >> > > >> > lkml.kernel.org/r/CABPqkBRbst4sgpgE5O_VXt-CSC0VD=ap2kwa0e3uy64tw7d...@mail.gmail.com > >> > > >> > I missed that 3 lines if they were in here. > >> > > >> I did not put them in there because there is another problem. > >> If you partition the generic counters 2 and 2, then some CPUs will not > >> be able to measure some events. > >> Unfortunately, there is no way to partition the 4 counters such that > >> all the events can be measured by > >> each CPU. Some events or precise sampling requires counter 2 for > >> instance (like prec_dist). > >> That's why I did not put this fix in. > > > > Ah, I wasn't thinking about a hard partition, just a limit on the number > > of exclusive counters any one CPU can claim such as to not starve. Or is > > that what you were talking about? I feel not being able to starve > > another CPU is more important than a better utilization bound for > > counter scheduling. > > So you're saying, just limit number of used counters to 2 regardless > of which one they are.
used as in marked exclusive and forced empty on the other side. > So sometimes, this will avoid the problem aforementioned and sometimes > not. We can try that. How will this sometimes not avoid the starvation issue? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
