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lszfcp: associative array speeds up extended SCSI device list a lot

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The linear search in the nested loop over SCSI devices and over the indexed
array is still time consuming. So replace the indexed array with an
associative array. Build the array once outside of the nested loop by using
pathname expansion and extracting key and value from each item. Within
the SCSI device loop, an array entry is removed by means of the key without
linear search.

This commit is separate from the previous one so it is possible to revert
this one in case associative arrays would not be available and still get
the speed improvement from the indexed array in the previous commit.

Before:

$ time ~/git/s390-tools/zconf/lszfcp -De | wc -l
1036

real	0m17.605s
user	0m17.159s
sys	0m0.308s

After:

$ time ~/git/s390-tools/zconf/lszfcp -De | wc -l
1036

real	0m0.207s
user	0m0.175s
sys	0m0.032s

Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
This commit is contained in:
Steffen Maier
2023-07-21 18:25:02 +02:00
committed by Steffen Eiden
parent e6c73c9974
commit bdaef6e76d
1 changed files with 24 additions and 29 deletions
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53
zconf/lszfcp
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@@ -372,18 +372,28 @@ show_devices()
SCSI_DEVICE_LIST=`ls -d $SYSFS/devices/css0/*/*/host[0-9]*/*/`
fi
declare -a ZFCP_UNIT_ARRAY
declare -A ZFCP_UNIT_DICT
if $SHOW_EXTENDED; then
ZFCP_UNIT_ARRAY=( $SYSFS/devices/css[0-9]*/[0-9d]*/[0-9]*/0x*/0x* )
# remember original array size since array becomes sparse below
# so the array length seems to reduce but we still need to
# iterate the original indexe range to find all existing entries
ZFCP_UNIT_ARRAY_LENGTH="${#ZFCP_UNIT_ARRAY[@]}"
ZFCP_UNITS=false
for UNIT_PATH in "$SYSFS"/devices/css[0-9]*/[0-9d]*/[0-9]*/0x*/0x*; do
if [ "$UNIT_PATH" = "$SYSFS/devices/css[0-9]*/[0-9d]*/[0-9]*/0x*/0x*" ]; then
break # no match (as seen without nullglob)
else
ZFCP_UNITS=true
fi
STRIPPED_PATH=${UNIT_PATH}
L=${UNIT_PATH##*/}
STRIPPED_PATH=${STRIPPED_PATH%/*}
W=${STRIPPED_PATH##*/}
STRIPPED_PATH=${STRIPPED_PATH%/*}
A=${STRIPPED_PATH##*/}
ZFCP_UNIT_DICT["$A/$W/$L"]=${UNIT_PATH}
done
else
ZFCP_UNIT_ARRAY_LENGTH=0
ZFCP_UNITS=false
fi
if [ -z "$SCSI_DEVICE_LIST" ] && [ "$ZFCP_UNIT_ARRAY_LENGTH" -eq 0 ]; then
if [ -z "$SCSI_DEVICE_LIST" ] && ! "$ZFCP_UNITS"; then
if $SHOW_EXTENDED; then
echo "Error: No zfcp-attached SCSI devices found."
else
@@ -396,24 +406,9 @@ show_devices()
read WWPN < $SCSI_DEVICE_PATH/wwpn
read LUN < $SCSI_DEVICE_PATH/fcp_lun
# loop is NOP without $SHOW_EXTENDED.
# remove from ZFCP_UNIT_ARRAY if SCSI device exists
ZFCP_UNIT_PATH=""
for ((i=0; i < "$ZFCP_UNIT_ARRAY_LENGTH"; i++)); do
UNIT_PATH="${ZFCP_UNIT_ARRAY[i]}"
[ -z "$UNIT_PATH" ] && continue # skip unset elements
STRIPPED_PATH=$UNIT_PATH
L=${UNIT_PATH##*/}
STRIPPED_PATH=${STRIPPED_PATH%/*}
W=${STRIPPED_PATH##*/}
STRIPPED_PATH=${STRIPPED_PATH%/*}
A=${STRIPPED_PATH##*/}
if [ "$A/$W/$L" = "$ADAPTER/$WWPN/$LUN" ]; then
ZFCP_UNIT_PATH="$UNIT_PATH"
unset "ZFCP_UNIT_ARRAY[i]"
break # minor optimization, still O(n)
fi
done
ZFCP_UNIT_PATH="${ZFCP_UNIT_DICT[$ADAPTER/$WWPN/$LUN]}"
# remove from ZFCP_UNIT_DICT if SCSI device exists
unset "ZFCP_UNIT_DICT[$ADAPTER/$WWPN/$LUN]"
[ $LUN != ${PAR_LUN:-$LUN} ] && continue
[ $WWPN != ${PAR_WWPN:-$WWPN} ] && continue
@@ -426,7 +421,7 @@ show_devices()
[ "$SDEVSTATE" != "running" ] \
&& SDEVMARKER="$SDEVMARKER NotRunning"
else
# build manually because ZFCP_UNIT_ARRAY loop was NOP
# build manually because ZFCP_UNIT_DICT is not used
ZFCP_UNIT_PATH=$SYSFS/devices/css[0-9]*/[0-9d]*/$ADAPTER/$WWPN/$LUN
fi
@@ -510,8 +505,8 @@ show_devices()
fi
done
# what's left in ZFCP_UNIT_ARRAY are now units without SCSI device
for UNIT_PATH in "${ZFCP_UNIT_ARRAY[@]}"; do
# what's left in ZFCP_UNIT_DICT are now units without SCSI device
for UNIT_PATH in "${ZFCP_UNIT_DICT[@]}"; do
STRIPPED_PATH=$UNIT_PATH
LUN=${UNIT_PATH##*/}
STRIPPED_PATH=${STRIPPED_PATH%/*}