WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] xc_domain_getinfolist() declaration

To: veillard@xxxxxxxxxx
Subject: Re: [Xen-devel] xc_domain_getinfolist() declaration
From: Anthony Liguori <aliguori@xxxxxxxxxx>
Date: Mon, 24 Oct 2005 14:27:52 -0500
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Mon, 24 Oct 2005 19:25:06 +0000
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <20051024150341.GQ2580@xxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <20051024150341.GQ2580@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla Thunderbird 1.0.7 (X11/20051013)
Daniel Veillard wrote:

I would expect xc_domain_getinfolist() to just be an extended version
of xc_domain_getinfo() but filling-up a range of xc_dominfo_t. However
the declaration in xenctrl.h is
 int xc_domain_getinfolist(int xc_handle,
                           uint32_t first_domain,
                            unsigned int max_domains,
                            xc_domaininfo_t *info);

i.e. a different info pointer type than

 int xc_domain_getinfo(int xc_handle,
                       uint32_t first_domid,
                        unsigned int max_doms,
                        xc_dominfo_t *info);

is that a typo ? xc_domaininfo_t is defined as dom0_getdomaininfo_t
which is a distinct type from xc_dominfo_t, with slightly different characteristics. Any reason for that disparity in the type returned
between those two functions ?
xc_domain_getinfolist is a batched interface to xc_domain_getinfo from the hypervisor perspective. That is, getinfolist will only make a single hypercall whereas getinfo will make up to max_doms hypercalls.

getinfo massages the returned data into a more python friendly structure (xc_dominfo_t) whereas getinfolist returns the raw results from the hypercall (which is just typedef'd to xc_domaininfo_t.

The argument for getinfolist was performance. Applications that require as low-overhead as possible polling info polling mechanism can use getinfolist.

Regards,

Anthony Liguori

Daniel



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>