Re: xfs: does mkfs.xfs require fancy switches to get decent performance? (was Tux3 Report: How fast can we fsync?)

From: Mike Galbraith
Date: Thu Apr 30 2015 - 09:48:23 EST

On Thu, 2015-04-30 at 05:58 -0700, Daniel Phillips wrote:
> On Thursday, April 30, 2015 5:07:21 AM PDT, Mike Galbraith wrote:
> > On Thu, 2015-04-30 at 04:14 -0700, Daniel Phillips wrote:
> >
> >> Lovely sounding argument, but it is wrong because Tux3 still beats XFS
> >> even with seek time factored out of the equation.
> >
> > Hm. Do you have big-storage comparison numbers to back that? I'm no
> > storage guy (waiting for holographic crystal arrays to obsolete all this
> > crap;), but Dave's big-storage guy words made sense to me.
> This has nothing to do with big storage. The proposition was that seek
> time is the reason for Tux3's fsync performance. That claim was easily
> falsified by removing the seek time.
> Dave's big storage words are there to draw attention away from the fact
> that XFS ran the Git tests four times slower than Tux3 and three times
> slower than Ext4. Whatever the big storage excuse is for that, the fact
> is, XFS obviously sucks at little storage.

If you allocate spanning the disk from start of life, you're going to
eat seeks that others don't until later. That seemed rather obvious and
straight forward. He flat stated that xfs has passable performance on
single bit of rust, and openly explained why. I see no misdirection,
only some evidence of bad blood between you two.

No, I won't be switching to xfs any time soon, but then it would take a
hell of a lot of evidence to get me to move away from ext4. I trust
ext[n] deeply because it has proven many times over the years that it
can take one hell of a lot (of self inflicted wounds;).


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