From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: xc_domain_getinfolist() declaration Date: Mon, 24 Oct 2005 14:27:52 -0500 Message-ID: <435D35B8.4060903@us.ibm.com> References: <20051024150341.GQ2580@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20051024150341.GQ2580@redhat.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: veillard@redhat.com Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org 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 > > >