Write data stream to SD-Card
 

My device receives a data stream. I want to write a C program to save this data stream to many files in a SD-Card. The SD-Card is formatted in FAT32 for a compatibility reason. I want to write full page of memory to aim to improve the write efficiency and get longer life of the SD-Card. Is it possible to lock the synchronization between the cache buffer and the storage device until the buffer is as long as the page size ? In other word, flush only full page of data ? Or I have to format the SD-Card to JFFS2 or YAFFS ?

Regards

Welcome to LQ. If you're writing C, that ought do be doable in your program. If you have to ask, you've failed the exam :-P. The system has it's own mind on matters, and doing that through the system is not on.

Thanks for your quick answer.

Yes, I'm writing in C. That was actually my idea to store temporary the data stream in a buffer, and when I have enough data (one page size), write them in the SD-Card :
write (fd, buffer, PAGE_SIZE);

But I was wondering if the OS really flushes the data in one time from the virtual memory to the hardware.

Maybe a other method it to map the memory :
mem = mmap (0, PAGE_SIZE, PROT_WRITE, MAP_SHARED, PAGE_SIZE * pageCounter);
memcpy (mem, buffer, PAGE_SIZE);
munmap (mem, PAGE_SIZE);

But again, my question is the same, does the OS flush in one time from the virtual memory to the hardware ? I hope so with the MAP_SHARED flag.

If you're writing C make sure to install the info pages from your distro, as they have entries for the various function calls. There is a HOWTO and several guides on programming for linux. People will expect you to have a knowledge of that stuff before you start asking. I will bow out here, as C is not hugely my thing.