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Re: [libvirt] [PATCH 1/3] numad: Convert node list to cpumap before setting affinity



On Wed, Apr 11, 2012 at 10:40:32PM +0800, Osier Yang wrote:
> Instead of returning a CPUs list, numad returns NUMA node
> list instead, this patch is to convert the node list to
> cpumap before affinity setting. Otherwise, the domain
> processes will be pinned only to CPU[$numa_cell_num],
> which will cause significiant performance losing.

  s/losing/losses/

> Also because numad will balance the affinity dynamically,
> reflecting the cpuset from numad back doesn't make much
> sense then, and it may just could produce confusion for
> users' eyes. Thus the better way is not to reflect it back

  confusion for the users.

> to XML. And in this case, it's better to ignore the cpuset
> when parsing XML.
> 
> The codes to update the cpuset is removed in this patch
> incidentally, and there will be a follow up patch to ignore
> the manually specified "cpuset" if "placement" is "auto",
> and document will be updated too.
> 
> ---
> The patch is tested on a NUMA box with 4 cells, 24 CPUs.
> ---
>  src/qemu/qemu_process.c |   33 ++++++++++++++++++++-------------
>  1 files changed, 20 insertions(+), 13 deletions(-)
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 481b4f3..0bf743b 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -1819,36 +1819,43 @@ qemuProcessInitCpuAffinity(struct qemud_driver *driver,
>      }
>  
>      if (vm->def->placement_mode == VIR_DOMAIN_CPU_PLACEMENT_MODE_AUTO) {
> -        char *tmp_cpumask = NULL;
>          char *nodeset = NULL;
> +        char *nodemask = NULL;
>  
>          nodeset = qemuGetNumadAdvice(vm->def);
>          if (!nodeset)
>              return -1;
>  
> -        if (VIR_ALLOC_N(tmp_cpumask, VIR_DOMAIN_CPUMASK_LEN) < 0) {
> +        if (VIR_ALLOC_N(nodemask, VIR_DOMAIN_CPUMASK_LEN) < 0) {
>              virReportOOMError();
>              return -1;
>          }
>  
> -        if (virDomainCpuSetParse(nodeset, 0, tmp_cpumask,
> +        if (virDomainCpuSetParse(nodeset, 0, nodemask,
>                                   VIR_DOMAIN_CPUMASK_LEN) < 0) {
> -            VIR_FREE(tmp_cpumask);
> +            VIR_FREE(nodemask);
>              VIR_FREE(nodeset);
>              return -1;
>          }
>  
> -        for (i = 0; i < maxcpu && i < VIR_DOMAIN_CPUMASK_LEN; i++) {
> -            if (tmp_cpumask[i])
> -                VIR_USE_CPU(cpumap, i);
> +        /* numad returns the NUMA node list, convert it to cpumap */
> +        int prev_total_ncpus = 0;
> +        for (i = 0; i < driver->caps->host.nnumaCell; i++) {
> +            int j;
> +            int cur_ncpus = driver->caps->host.numaCell[i]->ncpus;
> +            if (nodemask[i]) {
> +                for (j = prev_total_ncpus;
> +                     j < cur_ncpus + prev_total_ncpus &&
> +                     j < maxcpu &&
> +                     j < VIR_DOMAIN_CPUMASK_LEN;
> +                     j++) {
> +                    VIR_USE_CPU(cpumap, j);
> +                }
> +            }
> +            prev_total_ncpus += cur_ncpus;
>          }
>  
> -        VIR_FREE(vm->def->cpumask);
> -        vm->def->cpumask = tmp_cpumask;
> -        if (virDomainSaveStatus(driver->caps, driver->stateDir, vm) < 0) {
> -            VIR_WARN("Unable to save status on vm %s after state change",
> -                     vm->def->name);
> -        }
> +        VIR_FREE(nodemask);
>          VIR_FREE(nodeset);
>      } else {
>          if (vm->def->cpumask) {

  ACK, but fix the commit message, and wait to see the feedback on 2/3
  and 3/3 as this should not be commited in isolation

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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