Adds option to switch between total counters and interval counters by pressing 't' key. Total counters show status since the start of application while interval counters show status since last refresh. Signed-off-by: Krzysztof Karas <krzysztof.karas@intel.com> Change-Id: I9b00c85a7c6609977723f632dda9111cf9a1bfc2 Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/5507 Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com> Reviewed-by: Maciej Szwed <maciej.szwed@intel.com> Reviewed-by: Jim Harris <james.r.harris@intel.com> Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>