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Fix sketchybar memory indicator to show actual memory pressure

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The previous implementation included inactive/cached pages and used
"Pages stored in compressor" (uncompressed size), resulting in inflated
percentages (~88%) that didn't reflect actual memory pressure.

Now uses:
- Anonymous pages (matches Activity Monitor's "App Memory")
- Pages wired down (system memory)
- Pages occupied by compressor (actual RAM used, not uncompressed size)

Also switches to awk for arithmetic to avoid bash integer overflow on
systems with >4GB RAM.
This commit is contained in:
John Ogle
2025-12-08 14:34:22 -08:00
parent 7278dc8306
commit 04e1a8563c
1 changed files with 17 additions and 10 deletions
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27
home/roles/aerospace/default.nix
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@@ -599,21 +599,28 @@ in
};
# SketchyBar memory monitoring plugin
# Shows actual memory pressure (excludes file cache/inactive pages)
home.file.".config/sketchybar/plugins/memory.sh" = mkIf cfg.sketchybar.enable {
executable = true;
text = ''
#!/bin/bash
MEMORY_STATS=$(vm_stat)
PAGES_FREE=$(echo "$MEMORY_STATS" | grep "Pages free" | awk '{print $3}' | tr -d '.')
PAGES_ACTIVE=$(echo "$MEMORY_STATS" | grep "Pages active" | awk '{print $3}' | tr -d '.')
PAGES_INACTIVE=$(echo "$MEMORY_STATS" | grep "Pages inactive" | awk '{print $3}' | tr -d '.')
PAGES_WIRED=$(echo "$MEMORY_STATS" | grep "Pages wired down" | awk '{print $4}' | tr -d '.')
PAGES_COMPRESSED=$(echo "$MEMORY_STATS" | grep "Pages stored in compressor" | awk '{print $5}' | tr -d '.')
TOTAL_PAGES=$((PAGES_FREE + PAGES_ACTIVE + PAGES_INACTIVE + PAGES_WIRED + PAGES_COMPRESSED))
USED_PAGES=$((PAGES_ACTIVE + PAGES_INACTIVE + PAGES_WIRED + PAGES_COMPRESSED))
MEMORY_PERCENT=$((USED_PAGES * 100 / TOTAL_PAGES))
# Use awk for all arithmetic to avoid bash integer overflow on large RAM systems
# Memory pressure = Anonymous (app memory) + Wired + Compressor RAM
# - Anonymous pages: app-allocated memory (heap, stack) - matches Activity Monitor's "App Memory"
# - Wired: kernel/system memory that can't be paged out
# - Pages occupied by compressor: actual RAM used by compressor (NOT "stored in compressor")
TOTAL_RAM=$(sysctl -n hw.memsize)
MEMORY_PERCENT=$(vm_stat | awk -v total_ram="$TOTAL_RAM" '
/page size of/ { page_size = $8 }
/Anonymous pages/ { anon = $3 + 0 }
/Pages wired/ { wired = $4 + 0 }
/Pages occupied by compressor/ { compressor = $5 + 0 }
END {
used = (anon + wired + compressor) * page_size
printf "%.0f", used / total_ram * 100
}
')
${pkgs.sketchybar}/bin/sketchybar --set $NAME label="$MEMORY_PERCENT%"
'';