Originally posted by: Haichao

Hi everyone,

i have a question about the Memory Management in AIX 6.1.
I have

• 128 GB RAM and
• 70 GB Page Space.

The application i am running on this machine is doing some operations in perl. These are done only once a day and uses both memory and paging space. My problem now is that when the application is finished with its operations the memory and page space are not released but hold. And this means ofr the next time that i will get a memory and page space overflow. I heard something about AIX 6.1 having a feature that does not allow the memory to be freed in order to do a faster processing for the next time. Someone told me about the parameters maxperm and minperm and that these values control this feature.

Anyone has some suggestions which values i should use?

this is the vmo -a output:

ame_cpus_per_pool = n/a
ame_maxfree_mem = n/a
ame_min_ucpool_size = n/a
ame_minfree_mem = n/a
ams_loan_policy = n/a
force_relalias_lite = 0
kernel_heap_psize = 65536
lgpg_regions = 0
lgpg_size = 0
low_ps_handling = 1
maxfree = 1088
maxperm = 29293578
maxpin = 27041196
maxpin% = 80
memory_frames = 33554432
memplace_data = 2
memplace_mapped_file = 2
memplace_shm_anonymous = 2
memplace_shm_named = 2
memplace_stack = 2
memplace_text = 2
memplace_unmapped_file = 2
minfree = 960
minperm = 976450
minperm% = 3
nokilluid = 0
npskill = 138240
npswarn = 552960
numpsblks = 17694720
pinnable_frames = 31259644
relalias_percentage = 0
scrub = 0
v_pinshm = 0
vmm_default_pspa = 0
wlm_memlimit_nonpg = 1

and this is the vmostat -v output:

33554432 memory pages
32548422 lruable pages
30013582 free pages
7 memory pools
2295313 pinned pages
80.0 maxpin percentage
3.0 minperm percentage
90.0 maxperm percentage
1.6 numperm percentage
529395 file pages
0.0 compressed percentage
0 compressed pages
1.6 numclient percentage
90.0 maxclient percentage
529395 client pages
0 remote pageouts scheduled
1 pending disk I/Os blocked with no pbuf
4761910 paging space I/Os blocked with no psbuf
2484 filesystem I/Os blocked with no fsbuf
11444 client filesystem I/Os blocked with no fsbuf
312559 external pager filesystem I/Os blocked with no fsbuf

Best,

Haichao

Originally posted by: flodstrom

The max/minperm parameters are related to the file system caching AIX does. Unless you know exactly what you are doing you should not mess around with those settings.

I suspect that a large portion of the memory in your system is used for file system caching, which is normal behaviour of AIX and signs of a rather healthy system.

However if your system is paging a lot there may be problems such as memory leaks in your application. You might also want to verify that the daily perl runs terminate properly so they don't just hang and keep on growing in numbers for every day it is being run.

In either case I would advice you to not change or tune any kernel parameters.

Originally posted by: kyle@cmbchina.com

First, in AIXv6.1, argument '-a' does not give all the parameters of vmo, you need add '-F' to get all. And, the default setting is already in favor of computational memory.

Second, I don't think vmo para adjustment would help a lot if it is the perl program that keeps exhausting memory. Identify the top 5 memory consuming processes using

# svmon -P -t 5

And using

# vmstat 1

to see if thers's a lot paging activities.

Monitor data would show the thief.

Originally posted by: MarkTaylor

What is the exact error you are getting ? you might want to post some more stats and the exact error msg ..

vmstat 1 10
lsattr -EHl mem0
lsps -a
svmon -G
vmo -Fa | egrep "lru|max|min"

Also, check the errpt -a for paging space kills ..

From what I can see above you have a very small amount of filesystem cache and you have had lots of blocked paging space bug operations more info please ..

Rgds
Mark Taylor