Question about four kinds of pages in struct xc_dominfo

Question about four kinds of pages in struct xc_dominfo

[Meng Xu]

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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*?
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?

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!

Best,

Meng

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Re: Question about four kinds of pages in struct xc_dominfo

[Konrad Rzeszutek Wilk]

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

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Re: Question about four kinds of pages in struct xc_dominfo

[Meng Xu]

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Hi Konrad,

Thank you so much for your advice! Now I get the difference of those three
kinds of pages.

Your advice of using the git annotate is really helpful! :-)

Best,

Meng


2014/1/3 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
>
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xen.org
> > http://lists.xen.org/xen-devel
>
>

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