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Re: [Xen-devel] what's inside hypercall page?



> do_sched_op is self explaining: it is used for scheduling of the vcpu.
> A vcpu going to idle is using this hypercall. So any interrupt waking
> the vcpu up will seem to occur very near to the hypercall.

> do_xen_version is often used as a very fast way to execute the check
> for pending events in the hypervisor (kind of polling).

> do_multicall might run for a long time. So the hypervisor returns to
> the caller from time to time setting IP to the hypercall. The caller
> has the chance to react to interrupts and will then continue the
> hypercall.
>
>
> HTH, Juergen


Thanks for the replying. Does that mean we cannot predict when will these two hypercalls finish? I want to set up an interval to monitor the instructions (one time monitor per hypercall), so as to reduce the performance cost. This requires an accurate prediction of instructions' execution so as to avoid missing hypercalls. Is that possible? The main problem is the execution of syscall (0x050f), as each hypercall behaves different, how can I predict where will it go after the syscall returns?

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