This will be used by upcoming spdk_top application. Signed-off-by: Maciej Szwed <maciej.szwed@intel.com> Change-Id: I066567f0f14d70e6744821e8e805934a3d790882 Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/1235 Tested-by: SPDK CI Jenkins <sys_sgci@intel.com> Reviewed-by: Jim Harris <james.r.harris@intel.com> Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>