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Ingo Molnar wrote: > * Ingo Molnar <mingo@elte.hu> wrote: > > >>> dyntick-enabled guest: >>> - reduce the load on the host when the guest is idling >>> (currently an idle guest consumes a few percent cpu) >>> >> yeah. KVM under -rt already works with dynticks enabled on both the >> host and the guest. (but it's more optimal to use a dedicated >> hypercall to set the next guest-interrupt) >> > > using the dynticks code from the -rt kernel makes the overhead of an > idle guest go down by a factor of 10-15: > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 2556 mingo 15 0 598m 159m 157m R 1.5 8.0 0:26.20 qemu > > As usual, great news. > ( for this to work on my system i have added a 'hyper' clocksource > hypercall API for KVM guests to use - this is needed instead of the > running-to-slowly TSC. ) > What's the problem with the TSC? The only issue I'm aware of is that the tsc might go backwards if the vcpu is migrated to another host cpu (easily fixed). A pv clocksource makes sense in any case. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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