Messages in this thread | | | Date | Thu, 28 Feb 2002 21:12:48 +0100 | From | Pavel Machek <> | Subject | Re: Sync over loop devices takes ages? [2.4.17] |
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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.
Oh, but I *want* to do 1k filesystem test!
Performance seems okay in 2.4.19-pre?aa?.... And even 2.4.18 is slightly faster. [BTW it is fully cached (100MB test on 256MB machine) so 4k reads should not be such a big problem.] Pavel -- Casualities in World Trade Center: ~3k dead inside the building, cryptography in U.S.A. and free speech in Czech Republic.
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