[libvirt] [PATCH V2 1/2] libxl: fix reporting of maximum memory

[Joao Martins]

On 02/08/2017 10:24 PM, Jim Fehlig wrote:
> The libxl driver reports different values of maximum memory depending
> on state of a domain. If inactive, maximum memory value is reported
> correctly. When active, maximum memory is derived from max_pages value
> returned by the XEN_SYSCTL_getdomaininfolist sysctl operation. But
> max_pages can be changed by toolstacks and does not necessarily
> represent the maximum memory a domain can use during its active
> lifetime.
> 
> A better location for determining a domain's maximum memory is the
> /local/domain/<id>/memory/static-max node in xenstore. This value
> is set from the libxl_domain_build_info.max_memkb field when creating
> the domain. Currently it cannot be changed nor can its value be
> exceeded by a balloon operation. From libvirt's perspective, always
> reporting maximum memory with virDomainDefGetMemoryTotal() will produce
> the same results as reading the static-max node in xenstore.
> 
> Signed-off-by: Jim Fehlig <jfehlig at suse.com>

Acked-by: Joao Martins <joao.m.martins at oracle.com>

> ---
>  src/libxl/libxl_driver.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
> index 38ad91e..040b986 100644
> --- a/src/libxl/libxl_driver.c
> +++ b/src/libxl/libxl_driver.c
> @@ -1640,10 +1640,10 @@ libxlDomainGetInfo(virDomainPtr dom, virDomainInfoPtr info)
>      if (virDomainGetInfoEnsureACL(dom->conn, vm->def) < 0)
>          goto cleanup;
>  
> +    info->maxMem = virDomainDefGetMemoryTotal(vm->def);
>      if (!virDomainObjIsActive(vm)) {
>          info->cpuTime = 0;
>          info->memory = vm->def->mem.cur_balloon;
> -        info->maxMem = virDomainDefGetMemoryTotal(vm->def);
>      } else {
>          libxl_dominfo_init(&d_info);
>  
> @@ -1655,7 +1655,6 @@ libxlDomainGetInfo(virDomainPtr dom, virDomainInfoPtr info)
>          }
>          info->cpuTime = d_info.cpu_time;
>          info->memory = d_info.current_memkb;
> -        info->maxMem = d_info.max_memkb;
>  
>          libxl_dominfo_dispose(&d_info);
>      }
> @@ -5174,7 +5173,7 @@ libxlDomainMemoryStats(virDomainPtr dom,
>          goto endjob;
>      }
>      mem = d_info.current_memkb;
> -    maxmem = d_info.max_memkb;
> +    maxmem = virDomainDefGetMemoryTotal(vm->def);
>  
>      LIBXL_SET_MEMSTAT(VIR_DOMAIN_MEMORY_STAT_ACTUAL_BALLOON, mem);
>      LIBXL_SET_MEMSTAT(VIR_DOMAIN_MEMORY_STAT_AVAILABLE, maxmem);
>