SB memory pool misleading reporting and ES API confusing

[skliper]

Describe the bug
SB isn't reporting the peak and current memory pool use correctly.

To Reproduce
Inspect MemInUse and PeakMemInUse from SB (or UnmarkedMem which is max size - the peak in use) and compare to what's reported from ES from a status call in NumFreeBytes.

For example I just ran a test with the following results:

MemInUse = 30739
PeakMemInUse = 35418
Where the max size is set to 524288
But as reported from ES the NumFreeBytes is 459824

So the peak of blocks that were ever allocated is almost double the SB reported peak at 64464.

CFE_ES_GetPoolBufInfo claims to return "size of the buffer", but it returns ActualSize, not BlockSize. This could just be user confusion, but then CFE_ES_GetPoolGetBlockSize is the underlying call, and it also returns ActualSize,,not BlockSize.

I'd think the common use case of tracking the peak/unmarked memory in the pool is to manage margin. Since SB is just reporting a sum of the ActualSize's (aka the requested sizes) and not the actual used block sizes the real margin could be significantly less than what's implied by the SB reporting.

Expected behavior
There doesn't seem to be an API to show the peak for actual memory in use from ES, it's just the unmarked pool memory so I don't know that there's a way to really show exactly total used w/ current APIs but providing back the unmarked amount of memory seems more useful.

Code snips
SB tracking:

cFE/modules/sb/fsw/src/cfe_sb_buf.c

Lines 119 to 125 in 28a5820

	/* Add the size of the actual buffer to the memory-in-use ctr and */
	/* adjust the high water mark if needed */
	CFE_SB_Global.StatTlmMsg.Payload.MemInUse += AllocSize;
	if (CFE_SB_Global.StatTlmMsg.Payload.MemInUse > CFE_SB_Global.StatTlmMsg.Payload.PeakMemInUse)
	{
	CFE_SB_Global.StatTlmMsg.Payload.PeakMemInUse = CFE_SB_Global.StatTlmMsg.Payload.MemInUse;
	}

CFE_ES_GetPoolBufInfo calls CFE_ES_GenPoolGetBlockSize:

cFE/modules/es/fsw/src/cfe_es_mempool.c

Line 502 in 28a5820

Status = CFE_ES_GenPoolGetBlockSize(&PoolRecPtr->Pool, &DataSize, DataOffset);

But CFE_ES_GenPoolGetBlockSize returns the actual size:

cFE/modules/es/fsw/src/cfe_es_generic_pool.c

Line 419 in 28a5820

*BlockSizePtr = BdPtr->ActualSize;

System observed on:

• Hardware: Docker on PC
• OS: Ubuntu 22
• Versions: Close to main... project code

Additional context
NA

Reporter Info
Jacob Hageman - NASA/GSFC

[jphickey]

I concur that the TLM stats reported for pool usage is not great. They are hard to interpret and the common problems (i.e. fragmentation) are not apparent by looking at the numbers reported.