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Re: JFFS min_free_size




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On Fri, 16 Mar 2001, Stephen Brasher wrote:

> My question is, what is a reasonable fmc->min_free_size?

Good question. The code in question currently reads...

	/* min_free_size:
	   1 sector, obviously.
	   + 1 x max_chunk_size, for when a nodes overlaps the end of a sector
	   + 1 x max_chunk_size again, which ought to be enough to handle 
		   the case where a rename causes a name to grow, and GC has
		   to write out larger nodes than the ones it's obsoleting.
		   We should fix it so it doesn't have to write the name
		   _every_ time. Later.
	   + another 2 sectors because people keep getting GC stuck and
	           we don't know why. This scares me - I want formal proof
		   of correctness of whatever number we put here. dwmw2.
	*/
	fmc->min_free_size = fmc->sector_size << 2;

Theoretically, we should only require 2 * sector_size. In practice, that
sometimes wasn't enough, and we didn't reproduce the problem in-house so
didn't find out why, and I increased it to 4 * sector_size just to be on
the safe side.

-- 
dwmw2





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