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Full Discussion: semaphore access speed
Top Forums Programming semaphore access speed Post 302243827 by migurus on Monday 6th of October 2008 03:54:40 PM
Old 10-06-2008
Otheus, I never dealt with reporting on bugzilla, it seems ti me I don't quite qualify and I'm afraid I will post something not pertinent, so if you would agree to do it yourself, here are the results from 2nd version of your 'gettimeofday-based' code, which I re-run 4 times as to get average:

SCO
$ tmx2
575108.94 semop/s (5000000/8694005)
$ tmx2
575215.00 semop/s (5000000/8692402)
$ tmx2
575183.63 semop/s (5000000/8692876)
$ tmx2
559832.49 semop/s (5000000/8931243)

Linux:
$ ./tmx2
129363.77 semop/s (5000000/38650699)
$ ./tmx2
129428.22 semop/s (5000000/38631452)
$ ./tmx2
129601.55 semop/s (5000000/38579786)
$ ./tmx2
129511.76 semop/s (5000000/38606534)


As you see, no difference from the former tests.

Just for my clarification: somehow people who participated in this discussion on unix.com formu as well as on kerneltrap and other places were very concerned with 2 things, that in my perspective are irrelevant to the subject of this thread: time measurement accuracy and involvement of running multiple processes/shells etc that would muddy the results. I would wholeheartedly agree to that IF SCO vs Linux results were comparable. But this is not the case here. SCO is three times faster, no matter we used my method or gettimeofday very accurate method. With all the overhead being roughly similar, I would think we were kind of beating around the bush when we were trying to achieve have accuracy in measurement (which does not hurt, of cource!), but it made the thread bloated.

Again, thanks to Otheus for your suggestions, at this point I the kernel code you pinpoint shows that multi-cpu capability adds a layer of complexity and it does not help the speed. Your and strcmp's (kerneltrap forum) recomendations to upgrade Linux kernel are well taken.
migurus
 

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cdde.xml(5)															       cdde.xml(5)

NAME
cdde.xml - Configuration file for cdde DESCRIPTION
When cdde is run for the first time, an example xml configuration file (~/.cdde.xml) is created for you: <?xml version="1.0"?> <cdde delay="5000000"> <drive path="/dev/cdrom"> <audio command="echo An audio cd was inserted."/> <data command="echo A data cd was inserted."/> <dvd command="echo A dvd was inserted."/> <vcd command="echo A vcd was inserted."/> <svcd command="echo A svcd was inserted."/> <blank command="echo A blank cdr/dvdr was inserted."/> <mixed command="echo A mixed (audio/data) cd was inserted."/> </drive> </cdde> This default file is not very useful, and so I suggest you to edit it to your needs before running cdde again. You may add as many drive entries, or commands as you like. If multiple entries are found for a type of disc then all entries will be run in the order they are found. The specific device in use can be passed to the command with one of the following special tags: %dev% - is replaced with the device name of the cdrom that just had a disc inserted %mnt% - is replaced with the listed mount point for the cdrom that just had a disc inserted Note: %mnt% is determined through your fstab (usually located in /etc) file. If you do not have a listing for each <drive> in the fstab this will cause problems. This way, you can tell your video player which device to use when playing a VCD, for example. EXAMPLE
This is an example of ~/.cdde.xml file: <?xml version="1.0"?> <cdde delay="5000000"> <drive path="/dev/cdroms/cdrom0"/> <audio command="xmms %mnt%"/> <data command="mount %mnt%"/> <dvd command="xterm -iconic -e mplayer -fs -xineramascreen 1 -dvd 1"/> <vcd command="xterm -iconic -e mplayer -fs -xineramascreen 1 -vcd 1"/> <svcd command="xterm -iconic -e mplayer -fs -xineramascreen 1 -vcd 1"/> <blank command="gcombust"/> <mixed command="mount %mnt%"/> </drive> </cdde> FILES
~/.cdde.xml SEE ALSO
cdde(1) AUTHORS
Eric Lathrop <eric@ericlathrop.com> Stanislav Maslovski <stanislav.maslovski@gmail.com> WEBSITE
For the latest release of cdde, see: http://cdde.sourceforge.net/ Eric Lathrop 0.3.1 cdde.xml(5)
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