fix bytes/second io ops calculation

1 files changed, 27 insertions, 12 deletions

diff --git a/src/edit-firefox@ b/src/edit-firefox@
index 2fc99bd..9cf36f3 100755
--- a/src/edit-firefox@
+++ b/src/edit-firefox@
@@ -1,30 +1,44 @@
 #!/bin/bash
 
-TARGET=$1
+if [ "$1" = -f ]
+then
+    FORCE=y
+    shift
+fi
+
+if [ $# = 0 ]
+then
+    TARGET=/dev/stderr
+else
+    TARGET=$1
+fi
 
 die() { printf "%s: Error: %s\n" "$0" "$*" >&2; exit 1; }
 
-# Test DEVICE WRITE OPS BY WRITEOPS
-test_write_ops()
+# uses $DIR
+measure_write_speed()
 {
-    if ! [ -e "$1" ]
+    if [ "$FORCE" -o ! -e "$1" ]
     then
         mkdir -p "$(dirname "$1")"
         sync
         begin=$(date +%s%N)
-        dd if=/dev/urandom of="$DIR"/urandom.out bs=1M count=300
-        sync
+        count=500
+        dd if=/dev/urandom of="$DIR"/urandom.out bs=1M count=$count conv=fdatasync
         end=$(date +%s%N)
-        ops=$(( (end - begin) / 1000000000 ))
+        nanosecs=$(( end - begin ))
+        millisecs=$(( nanosecs / 1000 / 1000 ))
+        bytes=$(( count * 1000 * 1000 ))
+        bytes_per_second=$(( 1000 * bytes / millisecs ))
         rm "$DIR"/urandom.out
-        echo "$ops" > "$1"
+        printf "Sanity check: megabytes/second = %s\n" \
+               "$(( bytes_per_second / 1000 / 1000 ))" >&2
+        printf '%s\n' "$bytes_per_second" > "$1"
     fi
     cat "$1"
 }
 
 DIR=~/.mozilla
-READ_OPS=1G
-WRITE_OPS=$READ_OPS
 CONFDIR=$HOME/.config/firestart
 
 if [ -e "$CONFDIR"/conf ]
@@ -32,8 +46,9 @@ then
     . "$CONFDIR"/conf
 fi
 
-WRITE_OPS=$(test_write_ops "$CONFDIR"/diskspeed.dat)
-WRITE_OPS=${WRITE_OPS%.*}
+disk_write_speed=$(measure_write_speed "$CONFDIR"/diskspeed.dat)
+
+WRITE_OPS=$(( disk_write_speed / 2 ))
 READ_OPS=$WRITE_OPS
 
 [ -e "$DIR" ] || die "does not exist: $DIR"