Rich, The PGA is never contained within the SGA. In all architectures and on all platforms, it resides separate. The PGA holds process-specific data structures such as the "sort area", the "hash area", and some work areas used during bitmap-index operations.
In "shared-server" (formerly "multi-threaded server" or MTS) architecture, the UGA (a.k.a. "session/user global area", contains cursor-state and session-state info) can reside in the SGA, either in the Large Pool (if configured) or in the Shared Pool (by default). In "dedicated-server" architecture, the UGA is separate from the SGA. Hope this helps... -Tim ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Friday, November 29, 2002 6:48 AM > Jay, > > My understanding is that the PGA is contained within the SGA, and that > shmmax is the "maximum size of a single shared memory segment". If you > set shmmax to 256MB and configure 1GB SGA, you should see it allocate 4 > shared memory segments for that purpose. Some Unix variants have > limitations on the number of shared memory segments which can either be > created (AIX) or simultaneously accessed (HP-UX). I haven't done much > with Sun in the last few years so don't specifically know of the Solaris > limitations, but I'm sure there is probably something there to consider. > That's typically why you want to set shmmax as high as you realistically > can -- to reduce the NUMBER of segments you need to allocate for shared > memory. > > Your sysadmin also mentions turning on "priority paging" to give the > user processes access to the memory before the file cache (aka buffer > cache). Again I'm not sure about Solaris, but AIX and HP-UX both ship > with their buffer cache set to something like 10% - 20% of total memory > by default, which is a pretty good guess for a generic system when the > vendor has no idea what you'll be using it for specifically... however, > for large Oracle systems, I typically tune this back a bit, depending on > the memory in the system. Normally something in the 2-8% or 3-10% range > is sufficient. Remember, Oracle does all it's own buffering via > DB_BLOCK_BUFFERS so doesn't really need to rely on the system buffer > cache, even using filesystems (of course, raw devices completely bypass > the system buffer cache). > > You might want to see what he's got the two parameters set to which > control the size of the system buffer cache; sometimes reducing that > will help quite a bit with paging/swapping. > > Rich > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Miller, > Jay > > Sent: Saturday, November 23, 2002 1:49 PM > > To: Multiple recipients of list ORACLE-L > > Subject: Do user processes apply against shmmax limit? > > > > 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: Rich Holland > 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: Tim Gorman 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).
