Why migrate to new backend format

[Michael Meeks <michael ximian com>]

Hi Alex,

On Mon, 2003-10-06 at 08:31, Alexander Larsson wrote:
> On Mon, 2003-10-06 at 01:04, Havoc Pennington wrote:
> > So the fewer-files patch is the only immediate reason to change.
> 
> And why is using fewer files important?

	Primarily seek time; secondarily slack file space I guess.

	Seek time: I have ~350 .xml files in my ~/.gconfd, and also ~350
directories (unsuprisingly). Each directory or xml file occupies a
separate block, and there is a very significant cost to moving the heads
to many of them to read them; at least, so the previous discussion, and
my timings seem to show. [1]

	Slack file space: my ~/.gconf takes up ~2600 kb (du -k) but the sum of
the file sizes is far smaller [ how do I count that easily ? ] anyhow,
the average of the first 30 files is <350bytes each suggesting that
we're getting ~10% utilisation (4k blocks); or wasting 2Mb of slack
space per user ;-)

	HTH,

		Michael.

[1] - two consecutive runs on my machine of this:

[michael michael .gconf]$ time find ~/.gconf -name '*.xml' -exec cat {}
> /dev/null \;

real    0m4.303s
user    0m0.158s
sys     0m0.383s
[michael michael .gconf]$ time find ~/.gconf -name '*.xml' -exec cat {}
> /dev/null \;

real    0m0.538s
user    0m0.215s
sys     0m0.318s

-- 
 michael ximian com  <><, Pseudo Engineer, itinerant idiot