Shell Programming and Scripting

Hi Friends,

How to capture the value of %Comp and %Noncomp values from AIX using topas command. I tried lot, but i cannot capture the value.

I think you are using the wrong tool. Instead of topas run "vmstat" and use the "numperm%".

I hope this helps.

bakunin

Dear Bakunin,

Thanks for your reply.

Topas is performance monitoring tool in AIX, so that i ask you how to capture the % Comp and % noncomp from topas command.
From topas command output, i can see % Comp is 70% and % Noncomp is 20%.
But numperm% of vmstat is 21.3.
The values are differ.

numperm% denotes what (computational mem/non computational memory)

Kindly advice.

Yes, but "topas" is designed for interactive use only. If you want to skim the values from some output stream you should use "vmstat" rather than "topas" because "vmstat"s output is a character stream whereas "topas"s output is full of control characters necessary for the screen control.

First: what is computational and non-computational memory? Memory is allocated controlled by some "vmo" (see "man vmo") tunables: "minperm%", "maxperm%", "minclient", "maxclient", "lrud_file_repage", ... Basically the AIX kernel tries to put otherwise unused memory to some use dedicating some part (the tunables control how big this part is) of it to the file cache. "Computational memory" is the part of the memory in use given to running processes. "Non-Computational memory" is the memory used for file cache (and a few other buffers of minor significance). Together, computational and non-computational memory is "used memory".

"minperm%" and "maxperm%" control when and under which circumsteances non-computational memory is changed to computational memory and vice versa (which is done by the lrud-daemon), "numperm%" tells you, where - in between minperm and maxperm - you are right now.

After this rather lengthy explanations, here is a sample output of "vmstat -v" (AIX 7.1, idle system):

Code:

# vmstat -v 
             15073280 memory pages
             12080419 lruable pages
             13429620 free pages
                    3 memory pools
               850498 pinned pages
                 95.0 maxpin percentage
                  3.0 minperm percentage
                 90.0 maxperm percentage
                  4.4 numperm percentage
               536202 file pages
                  0.0 compressed percentage
                    0 compressed pages
                  4.4 numclient percentage
                 90.0 maxclient percentage
               536202 client pages
                    0 remote pageouts scheduled
                    5 pending disk I/Os blocked with no pbuf
                    0 paging space I/Os blocked with no psbuf
                 1972 filesystem I/Os blocked with no fsbuf
                    0 client filesystem I/Os blocked with no fsbuf
                    0 external pager filesystem I/Os blocked with no fsbuf
                  7.3 percentage of memory used for computational pages

I have marked the relevant lines bold: numperm percentage is the (%) amount of memory currently used by the file cache. Compare this to the number of totally allocated pages and you get the sizes of computational and non-computational memory. Note, that some numbers are percentages, some numbers are memory pages! Memory pages can be various sizes in AIX, but the most common are 4k. So, for instance, "2500" is roughly 10M.

I hope this helps.

bakunin

Thanks for your great explanation.

Thank you so much