>if that SGA + user processes > shmmax the system will start swapping.

That's not true.  If your SGA is bigger than shmmax, it just means
the SGA will be fit into multiple shared memory segments.  Doesn't
necessary mean the system will start swapping.  Is the scan rate
going up?

Richard

-----Original Message-----
Sent: Saturday, November 23, 2002 1:49 PM
To: Multiple recipients of list ORACLE-L


Hi everyone,

I was always under the impression that the only concern with shmmax was that
it be large enough for the SGA to fit into it. One of my System
Administrators has just told me that the individual user processes (i.e.,
the PGA since we're not using multi-threaded server) get added to the SGA
and if that SGA + user processes > shmmax the system will start swapping.

I haven't found anything to specifically address this issue on Metalink so I
though I'd throw it open. We've started experiencing  system slowdown and he
says that increasing shmmax could resolve it. I'm skeptical (he also
suggested increasing SGA to decrease swapping which I told him in no
uncertain terms was nonsense).

If anyone has a link to a note or white paper I'd appreciate that too. 

I've appended his email at the bottom. This slowdown seems to occur even
when there's virtually on oracle activity so I'm suspecting some other
cause.

Thanks,
Jay Miller

 

 
nycsun1 and njsun7 has 6 GB of memory and only 2 GB of share memory. This
morning nycsun1 was very slow and I noticed that there was lots of swaping.
see vmstst and iostat below in red:

procs     memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr s2 s4 s4 sd   in   sy   cs us sy
id
 0 0 23 4366736 97528 1 2186 16 12 12 95520 0 0 0 0  0 1104 3330  974 11  8
81
 0 0 23 4365992 96056 1 451 16 24 52 85968 3 0 0  0  0  935  847  416  3  1
96
 0 0 23 4364712 95512 2 310 36 24 492 85968 68 0 0 0 0 1036 2183  670 13  4
84
 0 0 23 4361568 95488 9 2264 0 76 964 95520 136 0 0 0 0 979 4065  607 12  6
82
 0 0 23 4362384 96080 1   6  4  8  8 77376 0 0 0  0  0  975  465  457  2  1
97
 0 0 23 4361944 95712 4 730 92 48 532 95520 64 0 0 0 0 1040 1859  734  8  3
89
 0 0 23 4360424 95480 4  41 36 40 100 77376 7 0 0 0  0  986 1250  542  6  0
94
 0 0 23 4361304 96096 3 264 76 36 88 88496 7 0 0  0  0 1037  942  665  5  3
92
 0 0 23 4359680 95784 2 449  4 28 84 95520 8 0 0  0  0  922 1047  374  4  1
95
 0 0 23 4359936 95464 2 544  4 20 332 95520 44 0 0 0 0  931 1095  384  2  2
96

/s  w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device
  0.0  0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c2t6d0
  0.0 34.5    0.0  270.0  0.2 13.8    6.7  399.5   6  44 c5t12d0 -- swap
disk
  0.0 34.5    0.0  270.0  0.5 10.7   15.5  309.4  18  39 c5t13d0 -- swap
disk


This shows that the system is not effectively using memory. I suggest
increasing the share memory to 4 GB so that DBAs can increase their memory
usage. Also set priority paging on. Priority paging will give application
first priority then free memory will be allocated to file cache( Solaris 2.6
and 7. Solaris 8 is set dynamically).

* ORACLE CONFIGS
set shmsys:shminfo_shmmax      =2048000000 -- increase to 4096000000
set shmsys:shminfo_shmmin=1
set shmsys:shminfo_shmmni=300
set shmsys:shminfo_shmseg=30
set semsys:seminfo_semmap=500
set semsys:seminfo_semmni=200
set semsys:seminfo_semmns=2000
set semsys:seminfo_semmsl=1000
set semsys:seminfo_semmnu=500
set semsys:seminfo_semume=150

 

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Miller, Jay
  INET: [EMAIL PROTECTED]

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Richard Ji
  INET: [EMAIL PROTECTED]

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).

Reply via email to