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

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(a)suse.com&gt;

--- 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);