Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [Patch] Cleanup struct gendisk registration, 2.3.40-pre1 | Date | Tue, 18 Jan 2000 08:15:13 +0100 |
| |
On Tue, Jan 18, 2000 at 06:07:28AM +0100, Andreas Dilger wrote: > [note email sent to linux-fsdevel, as it is OT for l-k] > Jamie Lokier writes: > > Alan Cox wrote: > > > Its caught errors before that probably avoided people losing data. Its a > > > good sanity check. The "stupid" defaults are two other things > > > > > > o Using 1K blocks on large disks (4K is way faster) and > > > 4K checks way faster too > > > > > > o Not using the "sparse superblock" option on large disks > > > when creating them. > > > > > > Unfortunately I dont think there are any "in place" fixers for those > > > creation time choices. > > > > Sparse superblocks can be turn on/off by the current tune2fs. > > You follow it by a fsck to clean up, then it's done. > > I was hoping they'd speed up the mount but its still takes an age... > > > > Why does 4k blocksize check faster? (I've never tried it). Does it use > > fewer superblocks? > > Not only are there 1/4 fewer (superblocks, group descriptors, inode/block > bitmaps) with 4k ext2 filesystems, but also files have fewer blocks, > including single-, double-, and triple-indirect blocks, so much less checking > for a given amount of data.
And much more waste. I recently discovered that a ~5GB 4K ext2 source code partition has ~480MB wasted in file tails. The same fileset (about 192k files) would only waste ~108MB with 1K blocks.
So sometimes 1K blocks or file tail packing (like in UFS or reiserfs) are a good idea. Unfortunately both are somewhat discouraged in 2.3 (the new IO paths seem to be heavily optimized for page sized IO only)
-Andi
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |