Added command-line option -r.

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@852 d57e44dd-8a1f-0410-8b47-8ef2f437770f

scripts/blockdev-perftest

@@ -27,17 +27,20 @@
 #########################
 
 function usage {
-  echo "Usage: $0 [-a] [-d] [-n] [-s <l2s>] <dev>"
+  echo "Usage: $0 [-a] [-d] [-n] [-r] [-s <l2s>] <dev>"
   echo "        -a - use asynchronous (buffered) I/O."
   echo "        -d - use direct (non-buffered) I/O."
   echo "        -n - do not verify the data on <dev> before overwriting it."
+  echo "        -r - only perform the read test."
   echo "        -s - logarithm base two of the I/O size."
   echo "        <dev> - block device to run the I/O performance test on."
 }
 
 function drop_caches {
   sync
-  echo 3 > /proc/sys/vm/drop_caches
+  if [ -w /proc/sys/vm/drop_caches ]; then
+    echo 3 > /proc/sys/vm/drop_caches
+  fi
 }
 
 
@@ -46,9 +49,10 @@ function drop_caches {
 #########################
 
 log2_io_size=30       # 1 GB
-log2_min_blocksize=12 # 4096 bytes
+log2_min_blocksize=9  # 512 bytes
 log2_max_blocksize=26 # 64 MB
 iotype=direct
+read_test_only=false
 verify_device_data=true
 
 
@@ -56,13 +60,14 @@ verify_device_data=true
 # Argument processing   #
 #########################
 
-set -- $(/usr/bin/getopt "adns:" "$@")
+set -- $(/usr/bin/getopt "adnrs:" "$@")
 while [ "$1" != "${1#-}" ]
 do
   case "$1" in
     '-a') iotype="buffered"; shift;;
     '-d') iotype="direct"; shift;;
     '-n') verify_device_data="false"; shift;;
+    '-r') read_test_only="true"; shift;;
     '-s') log2_io_size="$2"; shift; shift;;
     '--') shift;;
     *)    usage; exit 1;;
@@ -86,12 +91,12 @@ if [ ! -e "${device}" ]; then
   exit 1
 fi
 
-if [ ! -w "${device}" ]; then
+if [ "${read_test_only}" = "false" -a ! -w "${device}" ]; then
   echo "Error: device ${device} is not writeable."
   exit 1
 fi
 
-if [ "${verify_device_data}" = "true" ] \
+if [ "${read_test_only}" = "false" -a "${verify_device_data}" = "true" ] \
    && ! cmp -s -n $((2**log2_io_size)) "${device}" /dev/zero
 then
   echo "Error: device ${device} still contains data."
@@ -120,10 +125,14 @@ do
   printf "%9d " ${bs}
   for ((i=0;i<3;i++))
   do
-    drop_caches
-    elapsed="$(dd if=/dev/zero of="${device}" bs=${bs} count=${count} \
-                  ${dd_oflags} 2>&1 \
-               | sed -n 's/.* \([0-9.]*\) s,.*/\1/p')"
+    if [ "${read_test_only}" = "false" ]; then
+      drop_caches
+      elapsed="$(dd if=/dev/zero of="${device}" bs=${bs} count=${count} \
+                    ${dd_oflags} 2>&1 \
+                 | sed -n 's/.* \([0-9.]*\) s,.*/\1/p')"
+    else
+      elapsed=-1
+    fi
     printf "%8s " "${elapsed}"
   done
   for ((i=0;i<3;i++))