Re: 2.6.6-mm5 oops mounting ext3 or reiserfs with -o barrier

[Jens Axboe]

On Sun, May 23 2004, Lorenzo Allegrucci wrote:
> On Sunday 23 May 2004 12:03, Jens Axboe wrote:
> 
> > Here's a rolled up updated version that tries to get async notification
> > of missing barrier support working as well. reiser currently doesn't
> > cope with that correctly (fails mount), ext3 seems to but gets stuck.
> > Andrew has that fixed already, I think :-)
> >
> > Lorenzo, can you test this on top of 2.6.6-mm5?
> 
> Problem fixed, but there is some performance regression
> 
> ext3 (default)
> untar		read		copy		remove
> 0m53.861s	0m24.942s	1m30.164s	0m20.664s
> 0m7.132s	0m1.191s	0m0.766s	0m0.076s
> 0m5.807s	0m3.345s	0m9.996s	0m1.719s
> 
> ext3 (-o barrier=1)
> untar		read		copy		remove
> 0m52.117s	0m28.502s	1m51.153s	0m25.561s
> 0m7.231s	0m1.209s	0m0.738s	0m0.071s
> 0m6.117s	0m3.191s	0m9.347s	0m1.635s

Not sure what you mean here, but yes of course -o barrier=1 is going to
be slower than default + write back caching. What you should compare is
without barrier support and hdparm -W0 /dev/hdX, if -o barrier=1 with
caching on is slower then that's a regression :-)

-- 
Jens Axboe

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