On Fri, Nov 16, 2007 at 07:07:00AM +0100, Ingo Molnar wrote: > > * Micah Dowty <[EMAIL PROTECTED]> wrote: > > > > I am a bit at a loss as to how this could relate to the patch. This > > > looks like a load balance logic issue that causes the load > > > calculation to go wrong? > > > > My best guess is that this has something to do with the timing with > > which we sample the CPU's instantaneous load when calculating the load > > averages.. but I still understand only the basics of the scheduler and > > SMP balancer. All I really know for sure at this point regarding your > > patch is that git-bisect found it for me. > > hm, your code uses timeouts for this, right? The CPU load average that > is used for SMP load balancing is sampled from the scheduler tick - and > has been sampled from the scheduler tick for eons. v2.6.23 defaulted to > a different method but v2.6.24 samples it from the tick again. So my > guess is, your testcode behave similarly on 2.6.22 too, correct?
Interesting.. here are the kernels I've tested so far, not including the git-bisect run I did between 2.6.19 and 2.6.20: 2.6.17 - 2.6.19 - 2.6.19.7 - 2.6.20 + 2.6.21 + 2.6.22 - 2.6.23.1 + Here a "-" means that the problem does not occur (my test program uses 100% of both CPUs) and a "+" means that the test program leaves one CPU mostly idle. Unless I've made a mistake, 2.6.22 seems like the outlier rather than 2.6.23. Is this inconsistent with the scheduler tick hypothesis? Thanks, --Micah - 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/