[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PROPOSAL] Event channel for SMP-VMs: per-vCPU or per-OS?
On Wed, Oct 30, 2013 at 03:40:25PM +0800, Luwei Cheng wrote: [...] > > > > What I mean is that you will introduce latency / performance penalty > > from locks to protect critical sections. Say, if several CPUs contents > > for same event, overall performance might downgrade. > > > > I agree with you to some extent. But the question is: how frequently such > "contention" will happen? As explained, upcall handler is called only when > the processor switches from the hypervisor to the guest OS, and trapping > into the hypervisor are mostly caused by things like hypercall, IPI, etc. PV guest traps into hypervisor everytime it enables interrupt. > The probability that multiple switches happen "exactly" at the same same, > which I guess, is very small.. > It's not about "exactly at the same time", it's about we need to ensure the handler runs only once (takes effect only once). > Thanks, > Luwei _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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