Re: [Ext2-devel] [RFC 0/13] extents and 48bit ext3

Jeff Garzik
2006-06-10T01:43:26Z

Andreas Dilger wrote:
> On Jun 09, 2006 21:09 -0400, Jeff Garzik wrote:
>> Theodore Tso wrote:
>>> Jeff, you seem to think that the fact that the layout isn't precisely
>>> the same after an on-line resizing is proof of something horrible, but
>>> it isn't. The exact location of filesystem metadata has never been
>>> fixed, not in the past ten years of ext2/3 history, and this is not a
>>> big deal. It certainly isn't "proof" of on-line resizing being
>>> something horrible, as you keep trying to claim, without any arguments
>>> other than, "The layout is different!".
>> No, I was proving merely that it is _different_. And the values where
>> you see a _difference_ are the ones of which are no longer sized
>> optimally, after you grow the fs to a larger size.
>
> It sounds like you don't know what you are talking about, which is OK,
> except that you keep harping on some non-existent point.
>
>> So you incur a performance penalty for resizing to size S2, rather than
>> mke2fs'ing the new blkdev at size S2. Certainly within the confines of
>> ext3 that cannot be helped, but a different inode allocation strategy
>> could improve upon that.
>
> ??? Can you please be specific in what the performance penalty is, and
> what specifically is "not sized optimally" after a resize? How exactly
> does inode allocation strategy relate to anything at all to online resizing.

Inodes per group / inode blocks per group, as I've already stated.

Jeff