[libvirt] [PATCH v2 1/3] libxl: implement NUMA capabilities reporting

[Jim Fehlig]

Dario Faggioli wrote:
> Starting from Xen 4.2, libxl has all the bits and pieces in place
> for retrieving an adequate amount of information about the host
> NUMA topology. It is therefore possible, after a bit of shuffling,
> to arrange those information in the way libvirt wants to present
> them to the outside world.
>
> Therefore, with this patch, the <topology> section of the host
> capabilities is properly populated, when running on Xen, so that
> we can figure out whether or not we're running on a NUMA host,
> and what its characteristics are.
>
> [raistlin at Zhaman ~]$ sudo virsh --connect xen:/// capabilities
> <capabilities>
>   <host>
>     <cpu>
>     ....
>     <topology>
>       <cells num='2'>
>         <cell id='0'>
>           <memory unit='KiB'>6291456</memory>
>           <cpus num='8'>
>             <cpu id='0' socket_id='1' core_id='0' siblings='0-1'/>
>             <cpu id='1' socket_id='1' core_id='0' siblings='0-1'/>
>             <cpu id='2' socket_id='1' core_id='1' siblings='2-3'/>
>             <cpu id='3' socket_id='1' core_id='1' siblings='2-3'/>
>             <cpu id='4' socket_id='1' core_id='9' siblings='4-5'/>
>             <cpu id='5' socket_id='1' core_id='9' siblings='4-5'/>
>             <cpu id='6' socket_id='1' core_id='10' siblings='6-7'/>
>             <cpu id='7' socket_id='1' core_id='10' siblings='6-7'/>
>           </cpus>
>         </cell>
>         <cell id='1'>
>           <memory unit='KiB'>6881280</memory>
>           <cpus num='8'>
>             <cpu id='8' socket_id='0' core_id='0' siblings='8-9'/>
>             <cpu id='9' socket_id='0' core_id='0' siblings='8-9'/>
>             <cpu id='10' socket_id='0' core_id='1' siblings='10-11'/>
>             <cpu id='11' socket_id='0' core_id='1' siblings='10-11'/>
>             <cpu id='12' socket_id='0' core_id='9' siblings='12-13'/>
>             <cpu id='13' socket_id='0' core_id='9' siblings='12-13'/>
>             <cpu id='14' socket_id='0' core_id='10' siblings='14-15'/>
>             <cpu id='15' socket_id='0' core_id='10' siblings='14-15'/>
>           </cpus>
>         </cell>
>       </cells>
>     </topology>
>   </host>
>   ....
>
> Signed-off-by: Dario Faggioli <dario.faggioli at citrix.com>
> ---
> Changes from v1:
>  * fixed a typo in the commit message, as requested during review;
>  * fixed coding style (one function parameters per line and no spaces
>    between variable definitions), as requested during review;
>  * avoid zero-filling memory after VIR_ALLOC_N(), since it does that
>    already, as requested during review;
>  * improved out of memory error reporting, as requested during review;
>  * libxlMakeNumaCapabilities() created, accommodating all the NUMA
>    related additions, instead of having them within
>    libxlMakeCapabilitiesInternal(), as suggested during review.
> ---
>  src/libxl/libxl_conf.c |  141 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 140 insertions(+), 1 deletion(-)
>
> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
> index e170357..7515995 100644
> --- a/src/libxl/libxl_conf.c
> +++ b/src/libxl/libxl_conf.c
> @@ -161,6 +161,115 @@ libxlBuildCapabilities(virArch hostarch,
>  }
>  
>  static virCapsPtr
> +libxlMakeNumaCapabilities(libxl_numainfo *numa_info,
> +                          int nr_nodes,
> +                          libxl_cputopology *cpu_topo,
> +                          int nr_cpus,
> +                          virCapsPtr caps)
> +{
> +    virCapsHostNUMACellCPUPtr *cpus = NULL;
> +    int *nr_cpus_node = NULL;
> +    bool numa_failed = false;
> +    int i;
>   

BTW, the 'i' and 'j' iterators should be changed to size_t.  danpb has a
patchset to sanitize iterators that will be committed any time now, so
might as well make this change in your next version

https://www.redhat.com/archives/libvir-list/2013-July/msg00397.html

Regards,
Jim