From ce4539d465eba587aacd1c6b19e971950866f517 Mon Sep 17 00:00:00 2001
From: Adrian Sevcenco <adrian.sevcenco@cern.ch>
Date: Tue, 25 Jun 2019 10:17:55 +0300
Subject: [PATCH] utils/cms_monPerf : reduce all calls to awk and make
 measurements in parralel

---
 utils/cms_monPerf | 51 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/utils/cms_monPerf b/utils/cms_monPerf
index 48cd96dcb50..65381a68375 100755
--- a/utils/cms_monPerf
+++ b/utils/cms_monPerf
@@ -13,15 +13,22 @@
 INTERVAL="${1:-1}" # take as parameter the interval between runs, default to 1; NB! the loop take more than a few seconds to run
 NCPU=$(awk '/processor/ {nr++} END{print nr}' /proc/cpuinfo)
 
+# replace sleep subprocess
+snore() {
+    local IFS
+    [[ -n "${_snore_fd:-}" ]] || exec {_snore_fd}<> <(:)
+    read ${1:+-t "$1"} -u $_snore_fd || :
+}
+
 # return highest load (integer percentage) of either RX or TX
 IFACE_LOAD () {
     local iface="${1}"
     SPEED=$(< "${iface}"/speed)
-    [[ "$?" -ne 0 || ! "${SPEED}" -gt 0 ]] && return 1 # bail out if speed is not valid
+    [[ "$?" -ne 0 || ! "${SPEED}" -gt 0 ]] && { echo 0; return; } # just consider the interface load to be 0
 
     RX1=$(< "${iface}"/statistics/rx_bytes)
     TX1=$(< "${iface}"/statistics/tx_bytes)
-    sleep 1
+    snore 1
     RX2=$(< "${iface}"/statistics/rx_bytes)
     TX2=$(< "${iface}"/statistics/tx_bytes)
 
@@ -39,34 +46,48 @@ IFACE_LOAD () {
     } # end of function
 
 CPU_UTIL () {
-    # http://man7.org/linux/man-pages/man5/proc.5.html ; /proc/stat ; NB!! awk arrays start with 1
-    CPU_BEGIN=$(awk '/^cpu\s/ { printf "%d",$2 + $4 }' /proc/stat)
-    sleep 1
-    CPU_END=$(awk '/^cpu\s/ { printf "%d",$2 + $4 }' /proc/stat)
-    echo -ne $(( CPU_END - CPU_BEGIN))
+    # http://man7.org/linux/man-pages/man5/proc.5.html ; /proc/stat
+    read -a CPU_ARR_BEGIN < /proc/stat
+    snore 1
+    read -a CPU_ARR_END   < /proc/stat
+    awk -v ncpu="${NCPU}" -v CPU_BEGIN_USR="${CPU_ARR_BEGIN[1]}" -v CPU_BEGIN_SYS="${CPU_ARR_BEGIN[3]}" -v CPU_END_USR="${CPU_ARR_END[1]}" -v CPU_END_SYS="${CPU_ARR_END[3]}" 'BEGIN {
+    printf "%.0f",  (CPU_END_USR + CPU_END_SYS - CPU_BEGIN_USR - CPU_BEGIN_SYS)/ncpu ;
+    }' # ' end of awk
     }
 
 while(true); do # keep infinte loop
     LOAD5=$(awk -v ncpu="${NCPU}" '{ LOAD_PERC = $2*100/ncpu; printf "%.0f",LOAD_PERC; }' /proc/loadavg) #'
     [[ "${LOAD5}" -gt "100" ]] && LOAD5="100"
 
-    CPU=$(CPU_UTIL)
     MEM=$(awk '/MemTotal/{ MEM_TOT=$(NF-1) } /MemAvailable/ { MEM_AVAIL=$(NF-1) } END{ MEM_PERC = (MEM_TOT - MEM_AVAIL)*100/MEM_TOT; printf "%.0f",MEM_PERC; }' /proc/meminfo) #'
 
-    # should be replaced by IOwait/NCPU ?
+    # legacy, let's default to 0
     PGIO=0
 
-    NET_LOAD="0"
     IFACE_DIR="/sys/class/net"
-    for iface in ${IFACE_DIR}/*; do
+    LIST_OF_ETH=""
+    for iface in ${IFACE_DIR}/*; do # create a list of valid,physical and UP network interfaces
         [[ $(readlink -f "${iface}") =~ virtual ]] && continue
         OPERSTATE=$(< "${iface}"/operstate)
         [[ "$OPERSTATE" != "up" ]] && continue
-        LOAD=$(IFACE_LOAD "${iface}" || continue) # if IFACE_LOAD returns with exit=1 lets bail out
-        [[ "${LOAD}" -gt "${NET_LOAD}" ]] && NET_LOAD="${LOAD}" # keep NET_LOAD as maximum of all interfaces
+        [[ -z "${LIST_OF_ETH}" ]] && LIST_OF_ETH="${iface}" || LIST_OF_ETH="${LIST_OF_ETH} ${iface}"
+    done
+
+    exec {cpu_util}< <( CPU_UTIL )
+
+    NET_LOAD=0
+    LIST_OF_NET_FD=""
+    for iface in ${LIST_OF_ETH}; do
+        exec {iface_load}< <( IFACE_LOAD "${iface}" )
+        [[ -z "${LIST_OF_NET_FD}" ]] && LIST_OF_NET_FD="${iface_load}" || LIST_OF_NET_FD="${LIST_OF_NET_FD} ${iface_load}"
+    done
+
+    CPU=$(< /dev/fd/${cpu_util})
+    for NET_FD in ${LIST_OF_NET_FD}; do # select from all network interfaces the one with the biggest load
+        THIS_NET_LOAD=$(< /dev/fd/${NET_FD})
+        [[ "${THIS_NET_LOAD}" -gt "${NET_LOAD}" ]] && NET_LOAD=${THIS_NET_LOAD}
     done
 
     echo -ne "${LOAD5} ${CPU} ${MEM} ${PGIO} ${NET_LOAD}\n"
-    [[ "${INTERVAL}" -eq "0" ]] && break || sleep ${INTERVAL}
+    [[ "${INTERVAL}" -eq "0" ]] && break || snore ${INTERVAL}
 done # end of while loop
-