I am rather new to vxworks, and I am building an RTP application, which needs to allocate some memory dynamically. I have configured the kernel for a memory size of 750MB.
I am allocating memory in blocks 10 numbers each of size 32MB in the very beginning of the program, but after the 5th or 6th block allocation, I get an allocation failure with message memPartAlloc: block too big 15912260 bytes (0x10 aligned) in partition 0xe004608 on the console.
How could memory allocation be failing when there is enough memory available? I do not think memory had fragmented enough for allocation to fail right in the beginning of my program and as per output of memShow(), there is indeed enough free memory to satisfy the request.
If memory has indeed fragmented due to any strange reason, is there some way to compact free space and continue in Vxworks?
This is an old question, so this answer may be moot now, and is to an extent based on speculation based on the limited information in the question.
Whilst the kernel maybe configured to support 750MB, this will be the total memory available. Some of this will be used by the OS image, although we wont expect much, and we can assume that at least 700MB should be available for use.
Some extra memory will be used to provide the stacks for each task - how much is very application dependant, as it is specified in the taskSpawn. You can check this, but again, is unlikely to make significant difference.
Lets be generous, and assume that you really only have 650MB. This should, in theory, be plenty.
And yet we have this error:
memPartAlloc: block too big 15912260 bytes (0x10 aligned) in partition 0xe004608
What can be happening? And what does this mean? This error tells you that the memory allocator could not allocate memory, as the request was too large. Interestingly, the request is 15912260, which is not 32MB, it is actually a shade over 15MB. So it would be worth checking what you are actually requesting.
Secondly, this error message is coming from memPartAlloc. Are you using allocating memory using malloc() or memPartAlloc()? The distinction matters, since malloc will allocate memory from the system memory partition, whereas memPartAlloc allocates memory from a user-specifed, and created, partition.
If you are using memPartAlloc, ensure that you are allocating memory from the correct partition, and that it has been created with enough memory to fulfill the request.
EDIT:
As it appears that this was an RTP, you should also confirm that the RTP has a large enough heap allocated. This is specified via an environment variable, as this answer describes.