MAXTSIZ PARAMETER

[Nilzelio Monteiro]

I have a process that is growing. The kernel maxtsiz parameter was configured to 128Mb (it was 64Mb). I think that 128Mb is not a memory segment large enough to this process, because it has stopped due to out of memory.
My questions are:
What is the maximum value that I can configure the maxtsiz ? And what are the implications to the system?
The system has 512Mb of ram memory.

Thankx

[Vincenzo Restuccia]

maxtsiz
maxtsiz specifies the maximum shared-text segment size in bytes.

Acceptable Values:
maxtsiz for 32-bit processors:

Minimum
0x40000 (4 Mbytes)
Maximum
0x7B033000 (approx 2 Gbytes)
Default
0x4000000 (64 Mbytes)
maxtsiz_64bit for 64-bit processors:

Minimum
0x40000 (4 Mbytes)
Maximum
4398046511103 (approx 4 Gbytes)
Default
0x4000000 (64 Mbytes)
Specify integer value. For more information, see Specifying Parameter Values.

Description
maxtsiz and maxtsiz_64bit define, for 32-bit and 64-bit processors respectively, the maximum size of the shared text segment (program storage space) of an executing process. Program executable object code is stored as read-only, and thus can be shared by multiple processes if two or more processes are executing the same program simultaneously, for example.

The normal default value accommodates the text segments of most processes. Unless you plan to execute a process with a text segment larger than 64 Mbytes, do not modify maxtsiz or maxtsiz_64bit.

Each time the system loads a process with shared text, the system checks the size of its shared text segment. The system issues an error message and aborts the process if the process' text segment exceeds maxtsiz or maxtsiz_64bit.

See http://docs.hp.com/hpux/onlinedocs/os/KCparam.MaxTsiz.html

[Bill Hassell · Accepted solution]

Processes never grow in the text space. maxtsiz refers to the unchanging instructions in the program which is fixed at the time the program is compiled. The text quadrant is separate from the data area (maxdsiz) which indeed can grow as the program requires. The parameter you need to adjust is maxdsiz (and if your program is compiled as 64-bit code, maxdsiz_64).

These kernel parmeters exist as fences to prevent badly designed programs from consuming RAM and swap space. I would bump maxdsize to 500 megs for now and investigate what the program will eventually need as a maximum value. For a 32-bit program, addressability will be limited to apx 940 megs in the data area or with EXEC_MAGIC, about 1750 megs.

Make sure you have adequate swap space in case the program grows far larger than available RAM.