memory allocation: heaplow: Out of memory

[wmjenkinson]

Hello rsta2, I developing the schedular on circle and I have a task that allocates using malloc/new. However it keeps running out of memory. I've checked and there are no leaks. The code was working before porting to the RPI5. Is there something I am missing here to do with memory allocation?

[rsta2]

I'm not aware of fundamental differences of memory allocation between RPi 4 and 5. Please note that memory blocks of over 512 KBytes size won't be reused by default, when they were freed. You can dump the current allocation status with CMemorySystem::Get()->DumpStatus() to the logger. Blocks over 512 KBytes size are not included in this list.

[wmjenkinson]

Hello rsta2, for example, if I run this code the system will run out of memory!

while(true){

	uint8_t * temp = (uint8_t *)malloc(1000000);
	free(temp);
}

[rsta2]

Yes, that's the expected behavior, because memory blocks of over 512 KBytes size won't be reused by default, when they were freed. You can add a bucket for freed memory blocks of 1 MByte size here to change the behavior, like that:

#define HEAP_BLOCK_BUCKET_SIZES	0x40,0x400,0x1000,0x4000,0x10000,0x40000,0x80000,0x100000

Please read the comment above this option for explanation.

[wmjenkinson]

Thanks mate, can I ask. Who developed the Circle framework??

[rsta2]

Sure. Have a look into the CREDITS file and to the GitHub contributors page for the contributors to Circle. The project was started in 2014 by myself.

[wmjenkinson]

How many buckets exist by default. Is there a max or is it dynamically linked list?

[rsta2]

There are 7 values in HEAP_BLOCK_BUCKET_SIZES by default, so 7 buckets. The maximum is 20.