[Xen-devel] Anyone know how and where the do_sched_op(SCHEDOP_BLOCK) got called? -- Sam

[walmart <vmwalmart@xxxxxxxxx>]

Hi, all:

In the 64 bit Xen 4.0.1, compiled from the source code,

under xen/common/schedule.c,
ret_t do_sched_op(int cmd, XEN_GUEST_HANDLE(void) arg).

Does anyone know how this function got called?

I raise this question cause I noticed in the default credit based
scheduler, if I only configure one busy cpu to run(pinned to one
specific core, it is also the only VCPU on that core). if I run a busy
loop, I would only get 95% of the utilization.

I add some printk into the code and found that:

every 1s, the do_sched_op() would exec, and the cmd is schedop_block.
which would block the vcpu for 50 ms. (50 ms / 1 s = 5%), causing the
vcpu can only get 95% of the resources.

Does anyone know the reason for this?

Or, does anyone know how and where this do_sched_op() function get
called? I did a grep and all I can found is the compat_do_sched_op,
which is not called at all..

I would highly appreciate your help!

Thanks very much!

best!

Sam

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