Re: Question about four kinds of pages in struct xc_dominfo

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Dec 31, 2013 at 04:43:55PM -0500, Meng Xu wrote:
> Hi,
> 
> I'm trying to print out the "current used" pages of each domU.
> 
> I'm reading the xen code and found the data structure xc_dominfo at file
> tools/libxc/xenctrl.h.
> 
> *I have a simple, maybe very naive question: *
> 1) What is the difference among *nr_outstanding_pages*, * nr_shared_pages*,
> and *nr_paged_pages*?

The nr_outstanding_pages is usually zero. It means the amount of
pages that are needed for the guest to be allocated.

The nr_shared_pages - is the number of pages that are shared with other
guests or tools

The nr_ages_pages - that is if you page the pages to swap of a VM.
You need to use xenpaging for that.

> 2) Could anyone point me to a place that I can find the document of the
> definition of the structures in xen code, so that I can find those
> definition by myself?

Um, I usually use 'git annotate' on the file and the commit description
gives me a good idea

> 
> I'm new to the xen source and hope you can give me some guide to hack the
> xen code.
> 
> ========The structure is as below======================
> "tools/libxc/xenctrl.h"
> /*
>  * DOMAIN MANAGEMENT FUNCTIONS
>  */
> 
> typedef struct xc_dominfo {
>     uint32_t      domid;
>     uint32_t      ssidref;
>     unsigned int  dying:1, crashed:1, shutdown:1,
>                   paused:1, blocked:1, running:1,
>                   hvm:1, debugged:1;
>     unsigned int  shutdown_reason; /* only meaningful if shutdown==1 */
>     unsigned long nr_pages; /* current number, not maximum */
>     unsigned long nr_outstanding_pages;
>     unsigned long nr_shared_pages;
>     unsigned long nr_paged_pages;
>     unsigned long shared_info_frame;
>     uint64_t      cpu_time;
>     unsigned long max_memkb;
>     unsigned int  nr_online_vcpus;
>     unsigned int  max_vcpu_id;
>     xen_domain_handle_t handle;
>     unsigned int  cpupool;
> } xc_dominfo_t;
> 
> 
> Thank you very much for your time and help in these questions!
> Happy New Year!

You too!
> 
> Best,
> 
> Meng

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