Controlling the garbage collector (GC) at RT?

[Martin Egholm Nielsen]

> It seems to me that the only problem here is that this still
> seems to happen with overcommit-accounting set to 2.

> I would expect that you can reproduce this problem with a program
> that alternately allocates a few MB with sbrk, and then touches the
> allocated memory.  If you can't, there's something really weird going on
> here.  If you can, it'll give you a test case for the kernel people.
I tried the following:

#include <unistd.h>

int main( int i )
{
   while ( 1 ) {
     void *v = sbrk( 100000 );
     // sleep( 1 );
   } // while
} // main

But that doesn't result in anything - the memory usage for the 
application does not grow...
Are there anything else I should do to allocate the memory?

BR,
  Martin

> 
> Hans
> 
> On Wed, 16 Feb 2005, Martin Egholm Nielsen wrote:
> 
> 
>>Hi Hans,
>>
>>
>>>>>It would indeed be interesting to know why the Linux kernel
>>
>> >>>kills the application rather than returning failure.
>>
>>>>Sure, but how to do that? Any guidelines?
>>>
>>>What do you see on the console?  Anything in the system log?  Does
>>>strace tell you anything?
>>
>>Below is the last part of "strace -f -F -i -v". It doesn't really look
>>like there's anything of value?
>>
>>// Martin
>>
>>[pid    75] [0f833558] write(1, "*** MEM CHUNK TAKEN: 8388608\n", 29***
>>MEM CHUNK TAKEN: 8388608
>>) = 29
>>[pid    75] [0f839834] brk(0x12d15000)  = 0x12d15000
>>[pid    75] [0f839834] brk(0x12d25000)  = 0x12d25000
>>[pid    75] [0f81126c] getpid()         = 75
>>[pid    75] [0f799444] kill(77, SIGPWR <unfinished ...>
>>[pid    76] [0f840e2c] <... poll resumed> [{fd=3, events=POLLIN,
>>revents=POLLIN}
>>], 1, 2000) = 1
>>[pid    75] [0f799444] <... kill resumed> ) = 0
>>[pid    76] [0f81127c] getppid()        = 75
>>[pid    76] [0f833548] read(3,
>>"\20\7/\234\0\0\0\4\17\374$0\20\7/\240$\0\0B\17\3
>>72j(\177"..., 148) = 148
>>[pid    76] [0f840e2c] poll( <unfinished ...>
>>[pid    75] [0f799444] kill(77, SIGXCPU) = 0
>>[pid    75] [0f839834] brk(0x13525000)  = 0x13525000
>>[pid    75] [0f833558] write(1, "*** MEM CHUNK TAKEN: 8388608\n", 29***
>>MEM CHUNK TAKEN: 8388608
>>) = 29
>>[pid    75] [0f839834] brk(0x13535000)  = 0x13535000
>>[pid    75] [0f839834] brk(0x13545000)  = 0x13545000
>>[pid    75] [0f839834] brk(0x13d45000)  = 0x13d45000
>>[pid    75] [0f833558] write(1, "*** MEM CHUNK TAKEN: 8388608\n", 29***
>>MEM CHUNK TAKEN: 8388608
>>) = 29
>>[pid    76] [0f840e2c] <... poll resumed> [{fd=3, events=POLLIN}], 1,
>>2000) = 0
>>[pid    76] [0f840e2c] --- SIGTERM (Terminated) ---
>>#
>>
>>
> 
>