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тАО07-02-2002 02:10 AM
тАО07-02-2002 02:10 AM
We have been able to feel high wait rates to some processes with a high demand of ???I/O??? while processors (3 x 550Mhz CPU???s) show us high ???idle??? percentages. This makes me think that we should have some ???Kernel??? parameters are not appropriate with the new hardware/software characteristics and that they can be causing "trashing" in the system due to some high "paging" levels and lower CPU usage.
Please find attached a zip file with additional information about.
Solved! Go to Solution.
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тАО07-02-2002 02:24 AM
тАО07-02-2002 02:24 AM
Re: Low CPU usage and high wait rates
Pete
Pete
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тАО07-02-2002 02:32 AM
тАО07-02-2002 02:32 AM
SolutionAs I can see you have to high this parameter in your kernel.
dbc_max_pct 50 50 Static N/A
There are a lot of issues in this forum and the recomendations are from 5% to 10% depends on the total amount of memory in your system.
The minimun value must be 300MB, then you can try to put a low percentage, I sugest you that first try with 25% and look at the backup performance in order to know if this is a good percentage.
You can obtain more information about this parameter in the search section in this forum by trying dbc_max_pct.
Hope this helps,
Justo.
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тАО07-02-2002 02:37 AM
тАО07-02-2002 02:37 AM
Re: Low CPU usage and high wait rates
The reason swapper is so high is your system is very busy paging processes/memory out to disk and back. This is not a good situation to be in, it will slow down everything. You must reduce the memory pressure. As someone has pointed out your HP-UX buffer cache is too high(dbc_max_pct). Reduce it so that as a % of your total memory it wont use > than 300MB (not minimum as someone else said). Setting it to 300/350MB is fine.
After you do this and reboot your dont want to see the USED line for the device lines from swapinfo -mt > 0. This means no memory pressure and no paging. This will increase performance considerably.
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тАО07-02-2002 02:54 AM
тАО07-02-2002 02:54 AM
Re: Low CPU usage and high wait rates
This machine have 4Gb RAM
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тАО07-02-2002 03:14 AM
тАО07-02-2002 03:14 AM
Re: Low CPU usage and high wait rates
4Gb is on the low end for 11.0 64 bit. As previously pointed out, you need to reduce your memory pressure - probably by reducing your buffer cache (dbc_max_pct).
Pete
Pete