HP 50g & SD Cards: Performance, Format, Notes

[Claudio L.]

(08-08-2016 01:49 AM)JDW Wrote:  With the 256MB SD inserted (formatted FAT16, nothing on the card, only the one 256MB partition), it takes about 0.5s for the screen contents to display.

My last test on the 2GB card was a partition test.
With the card formatted that way in the 50g, the screen contents take the same 0.5s as my 256MB card.

Nice testing. There's one variable you didn't play with, though, and that's cluster size. The default cluster size will try to be as small as possible, which keeps the FAT table as large as possible. If the diskutil follows the MS recommendation in the link, means that:

Your 32 MB partition used 512 byte clusters --> approx 64k clusters in the FAT.
Your 256 MB partition used 4k byte clusters --> approx 64k clusters in the FAT.

This makes sense with your results: in both cases it needs about 0.5 sec to scan the whole FAT, as both FAT tables are almost identical sizes.

It would make sense for you to force for example 2k byte clusters on the 32 MB partition, which would make the FAT 4 times smaller. That is, if you want to reduce those 500 ms to an even smaller value. If you use a 256 MB partition on the 2GB card, it will probably still boot in the same amount of time because the FAT will be the same size too.