shmseg issue

[chindi]

Hi Guys,

I have a server rx4640 11iv2 with the following kernel paramters :

Tunable Usage / Setting
=============================================
dbc_max_pct 18 / 20
maxdsiz 16842752 / 1073741824
maxdsiz_64bit 138092544 / -2147483648
maxfiles_lim 47 / 8192
maxssiz 348160 / 134217728
maxssiz_64bit 786432 / 1073741824
maxtsiz 503808 / 134217728
maxtsiz_64bit 218103808 / 1073741824
maxuprc 140 / 3686
max_thread_proc 101 / 1024
maxvgs 3 / 255
msgmni 259 / 8212
msgseg 0 / 32767
msgtql 0 / 8212
nfile 3396 / 125228
nflocks 205 / 4096
ninode 1850 / 117744
nkthread 885 / 402404
nproc 485 / 8212
npty 0 / 512
nstrpty 13 / 512
nstrtel 0 / 512
nswapdev 2 / 10
nswapfs 0 / 10
semmni 55 / 16424
semmns 1401 / 32848
shmmax 96468992 / 100000000
shmmni 43 / 2048
shmseg 2010 / 120


Memory physical Memory = 8180 MB (7.988281 GB)
root #/ >sw
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 16000 101 15899 1% 0 - 1 /dev/vg00/lvol2
dev 16000 99 15901 1% 0 - 1 /dev/vg00/swap1
reserve - 8162 -8162
memory 8180 2488 5692 30%
total 40180 10850 29330 27% - 0 -

i have got two databses running one of oracle 9i SGA 400 MB & another oracle 10g SGA 500MB ..

kmeminfo shows ;

Physical memory usage summary (in page/byte/percent):

Physical memory = 2094092 8.0g 100%
Free memory = 8244 32.2m 0%
User processes = 1306765 5.0g 62% details with -user
System = 762981 2.9g 36%
Kernel = 366502 1.4g 18% kernel text and data
Dynamic Arenas = 193660 756.5m 9% details with -arena
vx_inode_cache = 38635 150.9m 2%
vx_global_pool = 19684 76.9m 1%
spinlock = 13825 54.0m 1%
mdep arena = 12431 48.6m 1%
M_TEMP = 9746 38.1m 0%
Other arenas = 99339 388.0m 5% details with -arena
Super page pool = 8398 32.8m 0% details with -kas
Static Tables = 133369 521.0m 6% details with -static
pfdat = 49080 191.7m 2%
nbuf = 38368 149.9m 2% bufcache headers
vhpt = 16384 64.0m 1%
inode = 9526 37.2m 0%
text = 7175 28.0m 0% vmunix text section
Other tables = 12835 50.1m 1% details with -static
Buffer cache = 396479 1.5g 19% details with -bufcache

Now my query is whether shmseg which is currrently 120 and being used 2010..
increasing it to 5000 resolve my memory crunch issue ???

Please advice...

[Dennis Handly]

>Now my query is whether shmseg which is currently 120 and being used 2010.

It does seem strange that the usage is above the limit. Did you recently reduce it?

>increasing it to 5000 resolve my memory crunch issue?

What crunch issue? Did you run swapinfo when your system was more idle?
You could reduce your buffer cache.

[chindi]

Hi Dennis,

Nickel of the same server before 6 mths attached herewith .

Recently i have installed glance from where i came to know this issue reg memory .


Increasing shmseg online a bit risky right ??

[Dennis Handly]

>Increasing shmseg online a bit risky right?

It should be safe.
Also if your segment size was larger, shmmax(5), you wouldn't need so many.

[vishnu.khandare]

Hi,

Can u share what are the process which are taking high memory, so that u can check where exactly memory crunch?


Regards
Vishnu Khandare

[chindi]

Hi Dennis,

Current shmmax 100000000
How much do you recommend ?? to make it safe ??

[chindi]

Hi Vishnu ,

From glance i get this thing attached hrewith .

[Dennis Handly]

>How much do you recommend?

You could try 1 Gb.

[chindi]

Hi Dennis,
U mean 1073741824 this value right ???

[Dennis Handly · Accepted solution]

>You mean 1073741824 this value right?

Yes.

[chindi]

Hi Dennis,

After changing the two parameters shmseg and shmmax i got a some free memory ...



Physical memory = 2094092 8.0g 100%
Free memory = 120513 470.8m 6%
User processes = 1171564 4.5g 56% details with -user
System = 786034 3.0g 38%
Kernel = 367216 1.4g 18% kernel text and data
Dynamic Arenas = 193662 756.5m 9% details with -arena
vx_inode_cache = 38635 150.9m 2%
vx_global_pool = 19738 77.1m 1%
spinlock = 13825 54.0m 1%
mdep arena = 12431 48.6m 1%
M_TEMP = 9746 38.1m 0%
Other arenas = 99287 387.8m 5% details with -arena
Super page pool = 8075 31.5m 0% details with -kas
Static Tables = 133689 522.2m 6% details with -static
pfdat = 49080 191.7m 2%
nbuf = 38688 151.1m 2% bufcache headers
vhpt = 16384 64.0m 1%
inode = 9526 37.2m 0%
text = 7175 28.0m 0% vmunix text section
Other tables = 12835 50.1m 1% details with -static
Buffer cache = 418818 1.6g 20% details with -bufcache


thnx Dennis for your valuable suggestions.