Re: [Xen-devel] ring buffer overflow

[David Xu <davidxu06@xxxxxxxxx>]

Hi,

This time I want to call it in the user-space. I wrote a user-level
application and call the xc_sched_credit_domain_set( int
 xc_handle, uint32_t domid, struct xen_domctl_sched_credit *sdom) in
it. But I don't know how to pass the xc_handle parameter in this
function. Thanks.

Regards,
Cong

2011/10/7 Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>:
> Stop top posting, I've asked you this before.
>
> On Fri, 2011-10-07 at 16:23 +0100, David Xu wrote:
>> Hi,
>>
>> I want to use the libxc function xc_sched_credit_domain_set( int
>> xc_handle, uint32_t domid, struct xen_domctl_sched_credit *sdom) in a
>> user-level application. But I don't know how to set the value of
>> xc_handle. Is there somebody familiar with it? Thanks.
>
> You can't use xc_* functions in the kernel, they are userspace. You
> could in theory look at the implementation of xc_sched_credit_domain_set
> to find out what that hypercall is and make the underlying hypercall
> instead, But:
>
> The hypercall in question here is a domctl which are not available /
> allowed from kernel space (for policy and semantic reasons rather than
> technological ones).
>
> As I explained elsewhere I don't think the architecture you have in mind
> is correct. I think you should look at exporting the necessary
> statistics from the kernel to userspace and have a daemon implement the
> logic and mechanisms for changing the scheduling parameters as required.
>
> Ian.
>
>
>

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