rewrite config

improved documentation, moved most common config options up front

service/zram-swap.config

@@ -1,22 +1,29 @@
-# override fractional calculations and specify a fixed swap size
-# don't shoot yourself in the foot with this, or do 🤷
-#_zram_fixedsize="2G"
-
-# portion of real ram to use as zram swap (expression: "1/2", "0.5", etc)
-_zram_fraction="1/2"
-
 # compression algorithm to employ (lzo, lz4, zstd, lzo-rle)
+# default: lz4
 _zram_algorithm="lz4"
 
-# expected compression ratio; this is a rough estimate
-#_comp_factor="2.5"
+# portion of system ram to use as zram swap (expression: "1/2", "2/3", "0.5", etc)
+# default: "1/2"
+_zram_fraction="1/2"
 
-# Note:
-# set _comp_factor by hand if you use an algorithm other than lzo/lz4/zstd or if your
-# use case produces drastically different compression results than my estimates
+# expected compression factor; set this by hand if your compression results are
+# drastically different from the estimates below
+#
+# Note: These are the defaults coded into /usr/local/sbin/zram-swap.sh; don't alter
+#       these values, use the override variable '_comp_factor' below.
 #
 # defaults if otherwise unset:
-#	lzo*|zstd)  _comp_factor="3"   ;;
-#	lz4)        _comp_factor="2.5" ;;
-#	*)          _comp_factor="2"   ;;
+#	lzo*|zstd)  _comp_factor="3"   ;; # expect 3:1 compression from lzo*, zstd
+#	lz4)        _comp_factor="2.5" ;; # expect 2.5:1 compression from lz4
+#	*)          _comp_factor="2"   ;; # default to 2:1 for everything else
 #
+#_comp_factor="2.5"
+
+# if set skip device size calculation and create a fixed-size swap device
+# (size, in MiB/GiB, eg: "250M" "500M" "1.5G" "2G" "6G" etc.)
+#
+# Note: this is the swap device size before compression, real memory use will
+#       depend on compression results, a 2-3x reduction is typical
+#
+#_zram_fixedsize="2G"
+