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lszfcp: eliminate costly child process for each SCSI device

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A simple built-in parameter expansion removing the matching prefix
pattern (everything up to and including the last slash) is sufficient to
strip the path from the basename.

Speeds up "lszfcp -D" significantly.

Before:

$ time ~/git/s390-tools/zconf/lszfcp -D | wc -l
1028

real	0m5.322s
user	0m0.300s
sys	0m4.907s

After:

$ time ~/git/s390-tools/zconf/lszfcp -D | wc -l
1028

real	0m0.602s
user	0m0.100s
sys	0m0.492s

Above measurements are from the fast in-memory sysfs. The improvements are
likely amplified when running "lszfcp --sysfs ..." on collected debug data
in a regular file system.

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
2022-12-02 23:58:02 +01:00
committed by Steffen Eiden
parent 63142e3051
commit 32dbfc4712
1 changed files with 1 additions and 1 deletions
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2
zconf/lszfcp
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@@ -422,7 +422,7 @@ show_devices()
fi
if [ $VERBOSITY -eq 0 ]; then
echo "$ADAPTER/$WWPN/$LUN `basename $SCSI_DEVICE_PATH`$SDEVMARKER"
echo "$ADAPTER/$WWPN/$LUN ${SCSI_DEVICE_PATH##*/}$SDEVMARKER"
else
echo "`ls -d $SYSFS/devices/css0/[0-9d]*/$ADAPTER`/$WWPN/$LUN"
echo ${SCSI_DEVICE_PATH%*/}$SDEVMARKER # without trailing slash