Messages in this thread | | | From | "Hans-Peter Jansen" <> | Subject | Re: Poor interactive performance with I/O loads with fsync()ing | Date | Mon, 12 Apr 2010 01:43:44 +0200 |
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On Sunday 11 April 2010, 23:54:34 Thomas Gleixner wrote: > On Sun, 11 Apr 2010, Andi Kleen wrote: > > > XFS does not do much better. Just moved my VM images back to ext for > > > that reason. > > > > Did you move from XFS to ext3? ext3 defaults to barriers off, XFS on, > > which can make a big difference depending on the disk. You can > > disable them on XFS too of course, with the known drawbacks. > > > > XFS also typically needs some tuning to get reasonable log sizes. > > > > My point was merely (before people chime in with counter examples) > > that XFS/btrfs/jfs don't suffer from the "need to sync all transactions > > for every fsync" issue. There can (and will be) still other issues. > > Yes, I moved them back from XFS to ext3 simply because moving them > from ext3 to XFS turned out to be a completely unusable disaster. > > I know that I can tweak knobs on XFS (or any other file system), but I > would not have expected that it sucks that much for KVM with the > default settings which are perfectly fine for the other use cases > which made us move to XFS.
Thomas, what Andi was merely turning out, is that xfs has a really concerning different default: barriers, that hurts with fsync().
In order to make a fair comparison of the two, you may want to mount xfs with nobarrier or ext3 with barrier option set, and _then_ check which one is sucking less.
I guess, that outcome will be interesting for quite a bunch of people in the audience (including me¹).
Pete
¹) while in transition of getting rid of even suckier technology junk like VMware-Server - but digging out a current², but _stable_ kernel release seems harder then ever nowadays. ²) with operational VT-d support for kvm -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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