load: do not attempt to infer CPU utilisation from load avgerage

Liquidprompt's load feature currently assumes, incorrectly, that the
load average is a percentage (it isn't) that can be converted directly
to CPU utilisation (it can't).

Because the load average is a gauge reading with an essentially
unlimited ceiling, ensure the colouring function is passed an
appropriate ceiling instead of the default value of 100. This ceiling is
now set (rather arbitrarily) at 20*$LP_LOAD_THRESHOLD, meaning the
"highest" colour starts being used at 18*$LP_LOAD_THRESHOLD.

To handle the case where the actual load exceeds the
20*$LP_LOAD_THRESHOLD ceiling, the _lp_color_map() function is changed
to apply the "highest" colour (instead of no colour) whenever the
supplied value exceeds the ceiling of the scale. This change is an
alternative implementation of what has already been proposed in liquidprompt#455.

Closes liquidprompt#499, liquidprompt#530.

Signed-off-by: Tore Anderson <[email protected]>

README.md

@@ -144,7 +144,7 @@ variety of Unix systems: `tput`, `grep`, `awk`, `sed`, `ps`, `who`, and `expr`.
 You can configure some variables in the `~/.config/liquidpromptrc` file:
 
 * `LP_BATTERY_THRESHOLD`, the maximal value under which the battery level is displayed
-* `LP_LOAD_THRESHOLD`, the minimal value after which the load average is displayed
+* `LP_LOAD_THRESHOLD`, the minimal value (centiload per cpu) after which the load average is displayed
 * `LP_TEMP_THRESHOLD`, the minimal value after which the average temperature is displayed
 * `LP_RUNTIME_THRESHOLD`, the minimal value after which the runtime is displayed
 * `LP_PATH_LENGTH`, the maximum percentage of the screen width used to display the path

liquidprompt

@@ -185,23 +185,23 @@ _LP_SED_EXTENDED=r
 # get current load
 case "$LP_OS" in
     Linux)
-        _lp_cpu_load () {
+        _lp_loadavg () {
             local eol
-            read lp_cpu_load eol < /proc/loadavg
+            read lp_loadavg eol < /proc/loadavg
         }
         ;;
     FreeBSD|Darwin|OpenBSD)
-        _lp_cpu_load () {
+        _lp_loadavg () {
             local bol eol
             # If you have problems with syntax coloring due to the following
             # line, do this: ln -s liquidprompt liquidprompt.bash
             # and edit liquidprompt.bash
-            read bol lp_cpu_load eol <<<"$( LC_ALL=C sysctl -n vm.loadavg )"
+            read bol lp_loadavg eol <<<"$( LC_ALL=C sysctl -n vm.loadavg )"
         }
         ;;
     SunOS)
-        _lp_cpu_load () {
-            read lp_cpu_load <<<"$( LC_ALL=C uptime | sed 's/.*load average: *\([0-9.]*\).*/\1/' )"
+        _lp_loadavg () {
+            read lp_loadavg <<<"$( LC_ALL=C uptime | sed 's/.*load average: *\([0-9.]*\).*/\1/' )"
         }
 esac
 
@@ -1399,6 +1399,8 @@ _lp_color_map() {
     scale=${2:-100}
     # Transform the value to a 0..${#COLOR_MAP} scale
     idx=_LP_FIRST_INDEX+100*$1/scale/${#LP_COLORMAP[*]}
+    # When off the scale, use the "highest" available color
+    (( idx < ${#LP_COLORMAP[*]} )) || idx=-1
     echo -nE "${LP_COLORMAP[idx]}"
 }
 
@@ -1479,21 +1481,20 @@ _lp_load_color()
 
     (( LP_ENABLE_LOAD )) || return
 
-    local lp_cpu_load
-    # Get value (OS-specific) into lp_cpu_load
-    _lp_cpu_load
+    local lp_loadavg centiload
+    # Get value (OS-specific) into lp_loadavg
+    _lp_loadavg
 
-    lp_cpu_load=${lp_cpu_load/./}   # Remove '.'
-    lp_cpu_load=${lp_cpu_load#0}    # Remove leading '0'
-    lp_cpu_load=${lp_cpu_load#0}    # Remove leading '0', again (ex: 0.09)
-    local -i load=${lp_cpu_load:-0}/$_lp_CPUNUM
+    centiload=${lp_loadavg/./}   # Remove '.'
+    centiload=${centiload#0}     # Remove leading '0'
+    centiload=${centiload#0}     # Remove leading '0', again (ex: 0.09)
+    local -i centiload_per_cpu=${centiload:-0}/$_lp_CPUNUM
 
-    if (( load > LP_LOAD_THRESHOLD )); then
-        local ret="$(_lp_color_map $load)${LP_MARK_LOAD}"
+    if (( centiload_per_cpu > LP_LOAD_THRESHOLD )); then
+        local -i ceiling=$LP_LOAD_THRESHOLD*20
+        local ret="$(_lp_color_map $centiload_per_cpu $ceiling)${LP_MARK_LOAD}"
 
-        if (( LP_PERCENTS_ALWAYS )); then
-            ret+="${load}${_LP_PERCENT}"
-        fi
+        ret+="${lp_loadavg}"
         echo -nE "${ret}${NO_COL}"
     fi
 }

liquidpromptrc-dist

@@ -16,7 +16,12 @@
 # Recommended value is 75
 LP_BATTERY_THRESHOLD=75
 
-# Display the load average when the load is above this threshold.
+# Display the load average over the past 5 minutes when above this threshold.
+# The value is expressed in centiload per CPU. For example, when using the
+# default value of 60, the load average will be displayed if above:
+# * 0.60 on a single-core machine, or
+# * 1.20 on a dual-core machine, or
+# * 2.40 on a quad-core machine, and so on.
 # Recommended value is 60
 LP_LOAD_THRESHOLD=60
 
@@ -58,9 +63,9 @@ LP_ENABLE_FQDN=0
 # users)
 LP_USER_ALWAYS=1
 
-# Display the percentages of load/batteries along with their
-# corresponding marks. Set to 0 to only print the colored marks.
-# Defaults to 1 (display percentages)
+# Display the battery percentage along with its
+# corresponding mark. Set to 0 to only print the colored mark.
+# Defaults to 1 (display percentage)
 LP_PERCENTS_ALWAYS=1
 
 # Use the permissions feature and display a red ':' before the prompt to show