Shared memory seems not in use - Mailing list pgsql-admin

Hi Guys,

I would really appreciate if someone could bring the light to this. Thank
you in advance. Here's my story:

postgresql-7.4.6
Linux Red Hat 9.0

I'm trying as anyone who ever installed Postgresql optimize it for speed.
After reading all those articles about increasing shared memory and tweaking
other params in postgesql.conf I ended up with :

Making 96MB shmax in Linux total
Making 96MB shmall in Linux total

Setting 8000 * 8 KB each for shared buffers in postgres conf
Setting sort_memory to 1024
Setting effective cache to 8MB in postgres conf
Decreasing connections number to 64
Checking Indexes in database scheme

And it did not seem affect in any way speed. The most confusing thing to me
that if I run Linux 'free' command it shows for shared memory usage 0bytes.
How it could come so? Here are my outputs:

[root@ns bin]# free
             total       used       free     shared    buffers     cached
Mem:        481268     473480       7788          0     117628      67424
-/+ buffers/cache:     288428     192840
Swap:       979956     889040      90916


[root@ns bin]# ipcs

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
0x0052e2c1 2654208    postgres  600        67960832   6
0x00000000 32769      root      600        92164      10         dest
0x00000000 2228226    root      600        524288     21         dest

------ Semaphore Arrays --------
key        semid      owner      perms      nsems
0x0052e2c1 25329664   postgres  600        17
0x0052e2c2 25362433   postgres  600        17
0x0052e2c3 25395202   postgres  600        17
0x00000000 5439491    apache    600        1
0x00000000 5472260    apache    600        1
0x00000000 5505029    apache    600        1
0x00000000 6029318    apache    600        1
0x00000000 6062087    apache    600        1
0x00000000 6094856    apache    600        1
0x00000000 12353545   apache    600        1
0x00000000 12386314   apache    600        1
0x00000000 12419083   apache    600        1
0x00000000 12779532   apache    600        1
0x00000000 12812301   apache    600        1
0x00000000 12845070   apache    600        1
0x00000000 17858575   apache    600        1
0x00000000 17891344   apache    600        1
0x00000000 17924113   apache    600        1
0x0052e2c4 25427986   postgres  600        17
0x0052e2c5 25460755   postgres  600        17
0x00000000 18972694   apache    600        1
0x00000000 19005463   apache    600        1
0x00000000 19038232   apache    600        1
0x00000000 19300377   apache    600        1
0x00000000 19333146   apache    600        1
0x00000000 19365915   apache    600        1
0x00000000 19955740   apache    600        1
0x00000000 19988509   apache    600        1
0x00000000 20021278   apache    600        1
0x00000000 21102623   apache    600        1
0x00000000 21135392   apache    600        1
0x00000000 21168161   apache    600        1
0x00000000 23035938   apache    600        1
0x00000000 23068707   apache    600        1
0x00000000 23101476   apache    600        1
0x00000000 24346661   apache    600        1
0x00000000 24379430   apache    600        1
0x00000000 24412199   apache    600        1
0x00000000 24510504   apache    600        1
0x00000000 24543273   apache    600        1
0x00000000 24576042   apache    600        1
0x00000000 24838187   apache    600        1
0x00000000 24870956   apache    600        1
0x00000000 24903725   apache    600        1

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages


Michael.