Re: Major mke2fs slowdown (reproducable, bisected)

[Alexey Dobriyan <adobriyan@gmail.com>]

On Mon, Nov 12, 2007 at 10:39:15AM -0800, Linus Torvalds wrote:
> On Mon, 12 Nov 2007, Alexey Dobriyan wrote:
> >
> > Cross-compile farm here migrated to .ccache and build dir on separate
> > disks and now I have a way to blow up .ccache without waiting half an
> > hour for rm(1) to finish. It's called mke2fs(8).
> > 
> > However, in e.g 2.6.24-rc2 mke2fs is amazingly slow if done right after
> > several fat cross-compile builds. Normally it takes ~11 seconds to
> > finish. After commit 5adc5be7cd1bcef6bb64f5255d2a33f20a3cf5be aka
> > "Bias the placement of kernel pages at lower PFNs" it takes several
> > minutes. 2.6.24-rc2 without this patch also gives normal mkfs speeds.
> > I'm pretty sure bisection wasn't screwed up.
> 
> Can you (just to make sure) do a "git revert" of this commit on top of the 
> current tree, and verify that that makes it all work fine again too? If 
> so, let's just revert it.
> 
> I just want to make sure that there isn't some subtle interaction with 
> anything else in there.

OK, with 2.6.24-rc2-6e800af233e0bdf108efb7bd23c11ea6fa34cdeb
mkfs took 4m6.915s seconds. With just "lower PFNs" patch reverted it's
back to 10 seconds.
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