Changing priority of a process

[PROSANJIT MALLICK]

We are running Informix Ver. 731F4 on K570 HpUX 11.00 Server. The problem
is users are complaining of slow response. The Informix administrators have
suggested to make the informix process as a System Process and this will
speed up the processing time leading to increase in system performance.

My query is what priority should be given to the Informix process. Also If a make it
a system process, how will my other system processes behave. Will it affect my
Server to the extent of damaging its file system leading to a crash.

What is the proper way of changing the priority of a process.

Any suggestions or advices will be highly appreciated.
Bye!

[John Palmer]

man nice - for running a process with a different priority.

man renice - change a running processes priority.

I wouldn't advise running any database process at a higher priority than the kernel.

Regards,

John

[Rick Garland]

Will need to lok at the 'nice' command. As to what the nice value of the Informix processes, this will depend on your environment. The other processes will fall behind this higher priority setting so there is some research involved involved as to what to set the nice at.

[Antoanetta Naghiu]

If the process is already running, you can change it proirity with renice comand. So, start it with, let say with nice 15 and degrease it if needed with renice to 10.
see man nice, man renice

[Tim Malnati]

I would be very careful about this. In most database environments response problems are usually a case where some users have started batch processes that are eating up resources. In general, it is better to nice these guys to a lower priority. Attempting to increase the priority of Informix is like trying to fool mother nature. The other system processes running have a need to run at the priority level that has been established, and fooling with this can cause things to go south very quickly.

If you don't have Glance, then I would push to get it asap. Glance will quickly point out the processing culprits and give you an indication of what the specific bottlenecks are. It's available on a trial basis from http://software.hp.com It is not unusual to find that your 'slow' response could just as easily be caused from a disk bottleneck from the culprits I mentioned above. In this case, nice with a lower priority will help, but not as much as you will probably desire. Unfortunately, nice only impacts CPU processing directly. HP has a PRM product that can be setup to help control things automatically, but again this product only effectively controls CPU. Disk issues are a lot more difficult to correct and usually will require the cooperation and effort of the DBA's to fix properly.

[Anthony deRito]

I would not recommend changing the priority of this process. It seems that your DBAs are at ends with increasing the performance of their databases and want to "try" something.

It is hard to tell you what other processes are going to suffer and what resources will be sacrificed from higher priority processes without knowing your system requirements.

I would push back and think about other performance issues with regards to database access, I/O... You will require a tool like Glance to analyze the process and see what the "bottleneck" really is. You can also use sar, vmstat and iostat for starts.

If your DBAs have relevant information regarding increasing the priority of the database processes, I am sure this forum would be glad to consider it.

Hope this helps,

Tony

[Alan Riggs]

I agree in principal with those above. Database performance issues often involve large queries claiming resources, degrading response time for other users. Even without glance, top should let you quickly determine which database sessions are claiming cpu resources (the only thing process priority is going to significantly affect).

In general, it is netter to *decrease* the priority of these large queries, freeing up more cpu cycles for interactive users with smaller demands.

In my experience, you get far more significant gains from identifying these queries and having the users/DBAs tune the sequels queries poperly than you ever will from changing process priorities.

[Vincente Fernandes]

HP has a product called PRM(Process Resource Manager)which can be used for processes priortisation. You have to buy it. I advice to think twice before assigning high priority to Informix process. Try installing Glance Plus(Paid S/W) to determine the exact cause. Also ask your DBA/Informix support to help in optimising your queries which will drastically improve your response time.