On Thu, Jul 2, 2009 at 2:55 PM, Michael Tokarev<mjt@xxxxxxxxxx> wrote: > kvm: i/o threads - should there be a way to control the amount of > threads? With default workload generated by drbd on secondary > node having less thread makes more sense. +1 on this. it seems reasonable to have one thread per device, or am i wrong? it also bothers me because when i have a couple of moderately disk-heavy VMs, the load average numbers skyrockets. that's because each blocked thread counts as 1 on this figure, even if they're all waiting on the same device. > kvm: it has been said that using noop elevator on guest makes sense > since host does its own elevator/reordering. But this example > shows "nicely" that this isn't always the case. I wonder how > "general" this example is. Will try to measure further. on my own (quick) tests, changing the elevator on the guest has very little effect on performance; but does affect the host CPU utilization. using drbd on the guest while testing with bonnie++ increased host CPU by around 20% for each VM -- Javier -- 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
