Large shared memory segments?

Large shared memory segments?

Post by Dave Haverka » Fri, 24 Mar 1995 04:00:47



I guess what I am actually confused on is in the Headers for the
sample code with W. Richard Stevens book "Unix Network Programming"
it has the following:

in "mesg.h"

* You may have to change the 4096 to a smaller value, if message queues
* on your system were configured with "msgmax" less than 4096.

#define        MAXMESGDATA     (4096-16)
                          /* we don't want sizeof(Mesg) > 4096 */

#define MESGHDRSIZE     (sizeof(Mesg) - MAXMESGDATA)
                                /* length of mesg_len and mesg_type */
--------------------------------
Anyhow, when I do a getpagesize() it returns 4096...  So, How does
the page size the system uses affect shared memory size, and other
IPC methods?

BTW, the headers on osf machines define SHMMAX   (4*1024*1024)
and on SUNOS 4.1.3 it is defined as 1024*1024.

--
David Haverkamp

 
 
 

1. What is this large share memory segment owned by root?

Hi,

My machine is running AIX 4.3.3.

I run the command ipcs -mb. and found :
T        ID     KEY        MODE       OWNER    GROUP     SEGSZ
Shared Memory:
m         0 0x0d05d2ee --rw-rw-rw-     root   system      1440
m         1 0x4704124c --rw-r--r-- informix informix        48
m         2 0x5804124c --rw-r--r-- informix informix      4096
m         3 0x4d04124c --rw-r--r-- informix informix      4096
m         4 0x4904124c --rw-r--r-- informix informix      4096
m         5 0x5004124c --rw-r--r-- informix informix      3222
m         6 0x45041253 --rw-rw-rw- informix informix        96
m         7 0x43041253 --rw-rw-rw- informix informix     97708
m         8 0x42041253 --rw-rw-rw- informix informix     36028
m         9 0x41041253 --rw-rw-rw- informix informix     42148
m        10 0x44041253 --rw-rw-rw- informix informix      2844
m    917515 0x081c90c4 --rw-r-----   oracle      dba  52850688
m   2228236 0x081c8245 --rw-r-----   oracle      dba 102694912
m        13 0x580550f1 --rw-rw-rw-     root   system 134217728
m        14 0x69041274 --rw-rw-rw-     prod     taps     25578

The segment with segment id 13 is very large, about 120MB.
m        13 0x580550f1 --rw-rw-rw-     root   system 134217728

What is this segment for? How can I know which program uses it?
How can I control it? say, reduce the size of it?

Many thanks.

Yerong

2. Strange spam (No linux content, I think)

3. Large shared memory segments?

4. help installing bsd 3.0

5. Large shared memory segments

6. MPEG Video PAL or NTSC output ?

7. Solaris 10: Increasing the process data space; shared memory segments & intimate shared memory problems

8. Dude, where's my network?

9. AIX Shared Memory Segment (Not enough memory)

10. Large Shared Memory, large files

11. can active shared memory segments be paged out ?

12. Shared Memory Segment Questions

13. Can I use a shared memory segment in mixed 32/64 bit mode