Memory allocation limit

[Gautam Shet]

Hi folks,
I am experiencing an unusual problem in that, I cannot allocate memory of size ~ 67 MB on a machine having 512 MB main memory. I am using the standard C routine malloc() to allocate the memory. BTW this is a 32 bit application.

Could it be some system setting that has some limitation set to the memory allocation?. I would apperciate any pointers to resolve this problem.

[Michael Tully]

Have a look at this posting:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=210579

[James Murtagh]

Hi Gautam,

The problem will be kernel tunable maxdsiz for malloc requests for 32bit processes. You haven't mentioned the OS but the default on 10.20 and 11.00 is 67MB, defined in /usr/conf/master.d/core-hpux ;

# grep MAXDSIZ core-hpux
maxdsiz MAXDSIZ 0x04000000
# echo 0x04000000=D|adb
67108864

On 11i the default is raised to 256MB.

Cheers,

James.

[Elmar P. Kolkman · Accepted solution]

It is 67 million bytes, which is in fact 64 Megabyte, depending on what you think of as Megabyte. In computer terms it is 1024 * 1024 bytes, while a lot of HD vendors think of Mb as 1000*1000 bytes...

So do a grep of maxdsiz in /stand/system. If it is not there, your limit is probably 64Mb (or 67108864) and you should start sam to change it if you are allowed to.

[Gautam Shet]

Hi folks,
Thanks for all your replies. Once I increased the value of maxdsiz to 256MB, using sam, the memory allocation went through fine.