[Scst-devel] SCST.pm profiling and optimalization

[Marcin H. <mar...@op...>]

Hi,

I tried to profiling and optimalizing scstadmin by changes SCST.pm 
module (for sysfs). After profiling I noticed a few subroutines which 
are used lots of time during one scstadmin command. After optimalization 
time for one scstadmin command I noticed decrese usage SCST.pm module 
for about ~40% to ~50%, and subroutines calls decrese notably too.

Results for one scstadmin command which remove iSCSI target:

Executed 13254 statements in 119ms

SCST::SCST::SCST_TARGETS_DIR() is called 772 times
SCST::SCST::drivers() is called 82 times
SCST::SCST::SCST_HANDLERS_DIR() is called 81 times
SCST::SCST::new_sysfs_interface() is called 78 times
SCST::SCST::targets() is called 28 times

After optimalization this results for remove iSCSI target commands decrese.

Executed 4854 statements in 64.2ms

SCST::SCST::SCST_TARGETS_DIR() is called 1 time
SCST::SCST::drivers() isi called 2 times
SCST::SCST::SCST_HANDLERS_DIR() is called 1 time
SCST::SCST::new_sysfs_interface() is called 1 time
SCST::SCST::targets() is called 4 times

To this message I attached result from profiling SCST.pm module by using 
'NYTProf' profiler and Perl 5.8.8. Profiling raport is for REMOVING 
iSCSI TARGET. There are two graphs and HTML files from profiler both for 
version without optimalization and for version with optimalization. In 
attachment prepared patch is available too.

In this case, need for optimalization SCST.pm module results from high 
availability service scripting.

Best regards
Marcin Haba