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Re: Re: Re: Possible PERL Issue, plz help...

by l2kashe (Deacon)
on Oct 16, 2003 at 18:46 UTC ( #299840=note: print w/ replies, xml ) Need Help??


in reply to Re: Re: Possible PERL Issue, plz help...
in thread Possible Perl Issue, plz help...

The fact that your proc jumps up that much is a decent sign. It more than likely means your process is not contending with any other processes for time on the proc. What I would be interested in seeing is the output from a vmstat 5 10. One prior to initating the process and another while the processes are running.

Without really looking into it too much, I want to point a finger at the I/O subsystem. I recently had similar problems with system utilities on a particular host. Come to find out the RAID controller was flaky. I couldn't see much of an issue, but it was the only thing I hadnt tested. So the disks got moved off of the hardware based controller, and ported over to software RAID. Viola the issue went away.

Its not much without a more fine tuned analysis of your particular system, but its another place to look. Seeing as how the same code runs flawlessly on a different host, it is on initial assumption more than likely hardware based. Another alternative route looking at a software level would be to use the 'strace' program to watch what is actually happening during runtime on that host. Its not the easiest tool to use at a 'junior' level, but will give great insights into whats going on.

use perl;


Comment on Re: Re: Re: Possible PERL Issue, plz help...
Re: Re: Re: Re: Possible PERL Issue, plz help...
by WeNdeL (Novice) on Oct 16, 2003 at 19:12 UTC
    I am planning on looking at the raid controller here soon. I have to bring the box down to do this so I will have to wait till early tomorrow morning. ugh... or maybe even this weekend... double ugh... *sigh*
    wendel@develop ~ $ vmstat 5 10 procs memory swap io system + cpu r b w swpd free buff cache si so bi bo in cs +us sy id 0 0 0 201948 51692 202216 452744 0 0 2 0 2 1 + 1 1 1 0 0 0 201948 51692 202228 452744 0 0 0 10 149 196 + 1 0 98 0 0 0 201948 51692 202228 452744 0 0 0 0 132 182 + 1 0 99 0 0 0 201948 51692 202228 452744 0 0 0 0 110 136 + 0 1 98 0 0 0 201948 51692 202232 452744 0 0 0 29 108 113 + 1 2 98 0 0 0 201948 51692 202232 452744 0 0 0 42 111 112 + 0 0 99 0 0 0 201948 51692 202232 452744 0 0 0 0 109 135 + 0 0 100 0 0 0 201948 51692 202232 452744 0 0 0 0 107 130 + 1 0 99 0 0 0 201948 51692 202232 452744 0 0 0 0 110 136 + 1 1 99 0 0 0 201948 51692 202232 452744 0 0 0 0 116 156 + 1 0 99 wendel@develop ~ $ vmstat 5 10 procs memory swap io system + cpu r b w swpd free buff cache si so bi bo in cs +us sy id 1 0 0 201936 92416 202284 452744 0 0 2 0 2 1 + 1 1 1 1 0 0 201936 83428 202296 452744 0 0 0 41 107 128 +19 1 80 0 0 0 201936 73672 202304 452744 0 0 0 50 106 121 +22 1 77 1 0 0 201936 78388 202312 452744 1 0 1 38 105 121 +17 2 81 1 0 0 201936 81252 202324 452744 0 0 0 42 109 133 +19 1 80 1 0 0 201936 84052 202328 452748 2 0 3 42 158 144 +22 2 76 1 0 0 201936 74168 202336 452748 1 0 1 73 141 161 +21 3 76 0 0 0 201936 63516 202348 452748 2 0 2 80 117 155 +24 1 75 0 0 0 201936 63516 202356 452748 0 0 0 42 111 138 + 0 1 99 0 0 0 201936 63516 202356 452748 0 0 0 0 130 185 + 0 0 99
    It seems as if the only big difference would be the number of blocks read in from disk. hrm... Raid controller... How did you move away from using the Raid controller? Did you get a different box? Disable it?

      Yeah. Everything looks good there, though I don't see the behaviour you noted with the proc going up to 100% utilized.

      Take a peek at the controller and see what happens. Im gonna put my money on it right now. (hopefully I dont lose ;) )

      use perl;


        Reason: BazB Delete: No value.

        For more information on this node visit: this

        So in my plans to look at the controller, I want to look at these things:

        1. What the Read-Ahead cache mode is. (on/off)

        2. What the stripe-unit size is. (8/16/32/64KB)

        3. How the hell to NOT use the Raid controller.

        Any help on number 3? Anything else to look at?

        I don't see the behaviour you noted with the proc going up to 100% utilized.

        Well, he did say that he saw 1 processor being used on a 4 processor system. It did bump up to 24% at one point. The fact that vmstat doesn't show CPU pegged at 25% is a good thing though. This doesn't seem to be CPU or IO bound...

        -sauoq
        "My two cents aren't worth a dime.";
        

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