Re: ext2 deletion times..

Matti Aarnio (matti.aarnio@sonera.fi)
Mon, 28 Jun 1999 01:10:01 +0300


On Sun, Jun 27, 1999 at 03:18:37PM -0400, Vladimir Dergachev wrote:
> Regarding the rm times for ext2:
> I would appreciate if people told me why this idea is stupid:
> - instead of storing pointers to individual blocks (as we do now)
> - store a pointer to first block in a segment and count of blocks
> in this segment. (or first and last block)

Yes, this is known as "extent mapping"
I did some analysis on the topic a while back, and got to a
concolusion that aside of certain constantly (slowly) growing
log files, most of my files in the system were under 6 extents.
...
> Of the stupid things I have missed is that this already got implemented
> since the last time I looked at ext2

Yes, once or twice, but never yet folded back into the kernel
proper. My own attempt, although it worked for me, wasn't
quite generic enough to be used in all cases. (And likely
was full of all kinds of hazards and races.)

Ted Ts'o is working on a generic approach where the metadata of
extents is stored on a BTREE datastructure.

> thanks
> Vladimir Dergachev

/Matti Aarnio <matti.aarnio@sonera.fi>

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