how to change shared memory

[bunty.....]

i need to shared memory from 1 GB to 8Gb.
i have physical memory of 32GB.

should i use sam.
then kcweb, then
shmmax value should i modify to 8589934592 from 1073741824?

thanks
bunty

[Patrick Wallek · Accepted solution]

Yes, that is one way to do it.

Keep in mind that 8GB of share memory will only be available if your application is a 64-bit application.

If you have 32-bit applications then there is a max of 4GB of RAM that they can use and that is for ALL 32-bit applications. The one caveat is if you use memory windows. Search the ITRC for white papers on memory management.

[Bill Hassell]

As Patrick mentioned, a 32bit ptogram can never address large amounts of memory. A simple 32bit program is limited to 1Gb, with compiler options they can reach about 1.75Gb, more with additional compile and/or chatr options. A 32bit program has access to 4 quadrants of 1Gb each, but less than half can be used for shared memory.

Note also that *all* 32bit programs that use shared memory must use the same map, so if one program set uses 1Gb of shared memory, another program set cannot get another 1Gb because the map is not large enough. Memory windows can help in this case. Here is the link Patrick mentioned: http://docs.hp.com/en/943/memwn1_4.pdf

If you recompile the programs as 64bit executables, all these restrictions go away.

[Steven E. Protter]

Shalom bunty

shmmax will ignore settings greater than 25% of memory.

memory is defined as ram plus swap.

On a 64 bit system you have a higher limit but the same basic rule.

SEP