Re: reiser4: first impression (vs xfs and jfs)

[PFC <lists@peufeu.com>]

> This may have been mentioned before, but perhaps there could be a
> "trickle-out" option along the lines of "if the hard drive is idle (and
> optionally only if it's spun up), slowly write out the changes to the
> disk structure."  This could also be paired with keeping as much of the
> data in memory as necessary to mantain the speed boost that r4 gets from
> temporal locality of reference, possibly just giving it to the system
> cache.

	Hm actually, this looks a lot like read-ahead algorithms, but instead  
it's "write-ahead" :

	For instance :
	- Sequential writes on large files should stream through the cache.
	- Random writes or small file writes should be kept as long as possible  
in dirty pages so they can be coalesced into larger writes with a better  
disk layout on flush, or not written at all if it was temp files from a  
make, for instance.

	Do the file copying programs open their output files with O_SEQUENTIAL ?  
If so, there is information to exploit...