From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Veillard <veillard@redhat.com>
Subject: Re: xc_domain_getinfolist() declaration
Date: Tue, 25 Oct 2005 04:27:31 -0400
Message-ID: <20051025082731.GU2580@redhat.com>
References: <20051024150341.GQ2580@redhat.com> <435D35B8.4060903@us.ibm.com>
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To: Anthony Liguori <aliguori@us.ibm.com>
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On Mon, Oct 24, 2005 at 02:27:52PM -0500, Anthony Liguori wrote:
> 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.

  Okay, thanks !

Daniel

-- 
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