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Re: Very high CPU utlization

 
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Sreekanth Makam
Occasional Advisor

Re: Very high CPU utlization

Hi Steve Lewis,

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Sreekanth Makam
Occasional Advisor

Re: Very high CPU utlization

Hi Steve Lewis,

I created indexes, done update stat..
All my queries are taking only index paths only.
I done database fragmentaion also. I distributed across 14 dbspaces. My whole databse is of 10GB. After this only actuall i got good reslts...

Any way..Thnks to all of them who participated in this...

Iam working in perfomance tuning on unix from last 1 year. So i will start new threads like this every day..Please participate in them. I am planing for this..Every day one topic will be there..Show your inteligence..And i will give realtime results for your thinkings...


***Let us share the knowledge****


Bye,
Sree
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Ted Buis
Honored Contributor

Re: Very high CPU utlization

There is a whole book entitled HP-UX 11i Performance and Tuning, by Robert F. Sauers. You can get it from Amazon. It will help you with methodology as well as tools. I would recommend you consider it.
The HP-UX Performance Cookbook has also been posted to this forum before but I guess I will attached again.
Mom 6
Bill Hassell
Honored Contributor

Re: Very high CPU utlization

Your code is likely causing the high system load. If there was a magic parameter that reduced the load, everyone would use it. But if your program is making a million calls to poll(2) every second, there's nothing you can do the kernel to reduce all the steps in the poll code...it has to execute and will consume time. I use poll as an example since there are two ways to determine if mailbox I/O is ready: poll as fast as you can (massive system overhead) or setup a wait and let the program get signaled when the I/O ready. Just an example...


Bill Hassell, sysadmin
Tim D Fulford
Honored Contributor

Re: Very high CPU utlization

Hi

A couple of things for you to look at

1 - what is the read:write ratio you should be reading more than writing. If not why are you writing data ypu will not read!!
2 - You say that you are using indexes everywhere. I hope you do not mean this 100%. For instance "select * from table where tag_id not like 100" is MOST efficient when sequentially scanning the table and avoiding the index.
3 - What are the service times on the disks? If the disks are slow then informix/application may be waiting on the slow disk. striping etc may help (depend on result)
4 - when you do "onstat -g glo" the cpu-vp's should be using the most resource, then aio-vps, everything else should be way below these. Make sure your shm-vp & soc-vp (if they exist) are NOT heavy uses of resource. If they are, then move the poll threads to the cpu-vps. From what you said you should have 8-9 cpu-vps & i'd use 8-9 poll threads of the appropriate protocol.
5 - lastly.. and probably should have been top of the list. Are you getting the workload out you hoped for? If so then Bils comment is on-the-button. Though I personally do not like to see cpu's above 80% on a regular basis as I like to have something in my back pocket!! (now I get the sales speach on iCOD.. I do know about this, just have not used it)

Regards

Tim
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Sreekanth Makam
Occasional Advisor

Re: Very high CPU utlization

hi tim,

1.The disk service time is less as iam fragmenting the tables across 12 db spaces which lie on diffrent disks. And keeping indexes across 4 db spaces. As aim using EVA SAN it will do striping by default.

If i watch dbspace utilization on onperf tool, all db spaces are utilizing uniformly.
Can you say what is the maximum number they can go. I mean no of read / wrties per second. By this i can conferm that disk is ok.

2. I checked onstat -g glo.. in that i observed

soc 41.19 461.68 502.87
soc 41.57 220.52 262.09
soc 42.56 230.36 272.92
soc 42.22 225.04 267.26
soc 43.88 236.15 280.03
soc 41.65 223.41 265.06

Can u coment anything on this...

3. Up to know glance plus was showing network bottelneck. Now after putting seperate test lan. It is solved.

***Problem is problem until u feel that is not a problem****




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Tim D Fulford
Honored Contributor

Re: Very high CPU utlization

Hi

skipping to the onstat -g glo..

you have 6 soc-vps evenly loaded(ish) What are the cpu-vps load in comparison? This is the key to tuning BALANCING the load. The best thing to post is the whole "onstat -g glo", but if you feel this is too much just the top bit which summarises the spead of the workload... to me your system should probably be optimised for local access (shared memory) and I'm guessing. If this is the case why do you have 6 soc-vps. My guess is that you may effectively have erronously assigned the soc-vps to the network vps (soc)
NETTYPE ipcshm,9,100,CPU
NETTYPE soctcp,6,100,CPU
NUMCPUVPS 9
This will assign the first 9 cpu-vps with shm-poll threads (sm_poll). The 6 socket poll threads WILL NOT go onto the cpu-vps so will end up as soc-vps (as yopu have). If this is you will need to decide what the split of shm connections & soc connections. say 2/3 1/3 split I would do the follwoing
NETTYPE ipcshm,6,100,CPU
NETTYPE soctcp,3,100,CPU
NUMCPUVPS 9
now all the poll threads will get onto each of the CPU-vps.

so to summarise
1 - onstat -g glo (the whole thing please)
2 - onstat -c or ONCONFIG would also be useful..

Timmmmy
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