SachinDesai
asked on
How to free up unused cache or memory space
Hi ,
I have a routine process which includes several bash scripts , perl programs and
other compiled programs which utilize a lot of memory. ( takes almost 32 hours to run )
Initially the process runs as expected , but after say 10 hours , i can see that the speed of processing has gone down drastically. I mean when i do a 'ps' i can see that the current script is utilizing only 1.6% CPU and takes hours to complete. Whereas if i run the same script alone , It utilizes sizable memory ( 95% CPU ) and completes within 15 minutes.
I guess i may have got some memory stuck or blocked ....
I have.....
RAM:1023 MB
SWAP : 3892 MB
OS : SunOS Release 5.8 Generic_108529-13
Ouestion: How do I release the memory without stopping the process or from within the process ( bashscript ) ? and also please note that I am not the Administrator.Any other related suggestions are also welcome.
I have a routine process which includes several bash scripts , perl programs and
other compiled programs which utilize a lot of memory. ( takes almost 32 hours to run )
Initially the process runs as expected , but after say 10 hours , i can see that the speed of processing has gone down drastically. I mean when i do a 'ps' i can see that the current script is utilizing only 1.6% CPU and takes hours to complete. Whereas if i run the same script alone , It utilizes sizable memory ( 95% CPU ) and completes within 15 minutes.
I guess i may have got some memory stuck or blocked ....
I have.....
RAM:1023 MB
SWAP : 3892 MB
OS : SunOS Release 5.8 Generic_108529-13
Ouestion: How do I release the memory without stopping the process or from within the process ( bashscript ) ? and also please note that I am not the Administrator.Any other related suggestions are also welcome.
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I'm a little confused.
> It utilizes sizable memory ( 95% CPU )
Memory and CPU are different entities. Just because it uses 95% CPU does not mean it uses lots of memory.
What I think you need to do is monitor the process throughout its life, recording the main system attributes during that period.
The first port of call is usually sar. There are heaps of parameters to sar, but run without any it will record the proportion of time the system is being used by usr and sys and the proportion spent waiting for io. Running it like this:
sar 60 1000 > sar.out
will run the reporting every 60 seconds for 1000 cycles (ie it will report once every 60 secs for 1000 minutes) and will output to file "logfile".
Have a look at the man page for sar for an explanation of the output.
If the CPU use goes right down, but the process still continues running, it could be that you are out of memory and starting to swap. Look at the paging stats from vmstat. As before:
vmstat 60 1000 > vmstat.out
The columns to look at are:
free free memory pages
swap free pages in swap
sr scan rate - indicates that the system is scanning memory for pages to move out into swap
po page out - pages being moved to swap
There are other tools available, for example prstat and mpstat. Take a look and see haow you get on.
> It utilizes sizable memory ( 95% CPU )
Memory and CPU are different entities. Just because it uses 95% CPU does not mean it uses lots of memory.
What I think you need to do is monitor the process throughout its life, recording the main system attributes during that period.
The first port of call is usually sar. There are heaps of parameters to sar, but run without any it will record the proportion of time the system is being used by usr and sys and the proportion spent waiting for io. Running it like this:
sar 60 1000 > sar.out
will run the reporting every 60 seconds for 1000 cycles (ie it will report once every 60 secs for 1000 minutes) and will output to file "logfile".
Have a look at the man page for sar for an explanation of the output.
If the CPU use goes right down, but the process still continues running, it could be that you are out of memory and starting to swap. Look at the paging stats from vmstat. As before:
vmstat 60 1000 > vmstat.out
The columns to look at are:
free free memory pages
swap free pages in swap
sr scan rate - indicates that the system is scanning memory for pages to move out into swap
po page out - pages being moved to swap
There are other tools available, for example prstat and mpstat. Take a look and see haow you get on.
Just to clarify something shivsa said. The file cache will occupy almost all free memory after the system has been in use for some time. However this is still effectively free memory, and so will be used by processes as they need it. There is no need to force it to be free.
At some stage (not sure if it is Solaris 8 or 9) the free memory reporting has been changed so that it counts file cache as free memory.
At some stage (not sure if it is Solaris 8 or 9) the free memory reporting has been changed so that it counts file cache as free memory.
As already mentioned in the about comments, you can not use script to FREE
process memory. "u may use good programming technique for memory management(free() up all the memory in code after using that and all).
Have a look at the following Solaris memory management doc:
http://tyrant112.tripod.com/overbeck/SolarisMem.htm
and
UNIX FAQ: -- Virtual Memory
http://argray.org/unixfaq/explain_vm.shtml
Performance tune:
http://oldlook.experts-exchange.com/questions/20498241/Solaris-8-Performance-Tuning.html
process memory. "u may use good programming technique for memory management(free() up all the memory in code after using that and all).
Have a look at the following Solaris memory management doc:
http://tyrant112.tripod.com/overbeck/SolarisMem.htm
and
UNIX FAQ: -- Virtual Memory
http://argray.org/unixfaq/explain_vm.shtml
Performance tune:
http://oldlook.experts-exchange.com/questions/20498241/Solaris-8-Performance-Tuning.html
Hi Sachin.
do u need more help here. please keep posted.
do u need more help here. please keep posted.
Sachin,
You can close the question by following this guidelines:
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You can close the question by following this guidelines:
https://www.experts-exchange.com/help.jsp#hs5
http://sunsite.uakom.sk/sunworldonline/swol-10-1995/swol-10-perf.html