Re: Controlling the garbage collector (GC) at RT?

[Martin Egholm Nielsen <martin at egholm-nielsen dot dk>]

> 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) ---
> > #