Messages in this thread | | | Date | Thu, 28 Feb 2002 10:05:34 -0800 | From | Andrew Morton <> | Subject | Re: Sync over loop devices takes ages? [2.4.17] |
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Pavel Machek wrote: > > Hi! > > I have a script (attached). At one point it tries to do sync... That > sync take a long time, with disk mostly unused.
When doing (say) ext2-on-loop-on-ext2 you should always ensure that the blocksize for the topmost filesystem is the same as the one underneath. So probably you wanted `mkfs.ext2 -b 4096'.
If you have a 1k blocksize filesystem loop-mounted on a 4k blocksize filesystem, every write of a 1k block requires a read of the underlying 4k block. Which is excrutiatingly slow.
Some readahead in the loop driver would help heaps.
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