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LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
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And that is exactly why Ted, being a practical person, reverted to the old behaviour in some situations. Doesn't mean application writers should continue using incorrect idioms.
> It's totally unrealistic and not doable in any short- or even mid-term. Why suggest this then? And who is irrational after all?
Sorry, fixing bugs is irrational?
> But all the blabbering about how POSIX allows this and stuff is unhelpful to end-user, if surely interesting and inspiring to developers.
POSIX isn't blabbering (see http://www.kernel.org/):
> Linux is a clone of the operating system Unix, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance.
This is a regression
Posted Mar 15, 2009 3:12 UTC (Sun) by bojan (subscriber, #14302)
1. By default make ext3 ordered mode have fsync as a no-op. People that want current broken behaviour could specify a mount option to get it.
2. Tell folks that they _must_ use fsync in order to commit their data.
3. Once critical mass of applications achieved the above, remove all hacks from ext4, XFS etc.
4. Retire ext3.
Posted Mar 15, 2009 4:53 UTC (Sun) by foom (subscriber, #14868)
Hopefully it can be the default fs for Ubuntu Jaded Jackal. If anyone complains, I'm sure "But POSIX
says it's okay to do that, the apps are broken for not obsessively calling sync after every write!" will
satisfy everyone. :)
Posted Mar 15, 2009 5:26 UTC (Sun) by bojan (subscriber, #14302)
All the people here suggesting that well established standards Linux _aims_ to implement should be ignored, should remember the screaming Microsoft had to face from the FOSS community when they started twisting various standards to their own ends.
Posted Mar 15, 2009 12:34 UTC (Sun) by nix (subscriber, #2304)
Posted Mar 15, 2009 21:09 UTC (Sun) by bojan (subscriber, #14302)
Of course, Ted put hacks into ext4 because application writers missed the above and it will take time to fix it. That's called a workaround.
Posted Mar 15, 2009 23:50 UTC (Sun) by nix (subscriber, #2304)
Agreed the apps are buggy, but I think this is a deficiency in POSIX,
rather than anything else.
Posted Mar 16, 2009 0:17 UTC (Mon) by bojan (subscriber, #14302)
And that's going to help the broken application running on another filesystem exactly how? The problem with hypocrisy here is not related to ext4 - it related to application code.
BTW, it is obvious that Ted already decided to make sure ext4 does that. The man is not stupid - he doesn't want the file system rejected over this - no matter how wrong the people blaming ext4 for this are.
> Agreed the apps are buggy, but I think this is a deficiency in POSIX, rather than anything else.
Well, yeah - the spec is, shall we say - demanding. But, it is what it is. We tell Microsoft not to ignore the specs. What makes us so special that we can? I would suggest nothing. If we take the right to demand that from Microsoft, we should make sure we do it ourselves.
Posted Mar 16, 2009 1:07 UTC (Mon) by nix (subscriber, #2304)
There's no point talking to you at all, IMNSHO.
Posted Mar 16, 2009 2:19 UTC (Mon) by bojan (subscriber, #14302)
If you don't want to talk to me, then don't. That's OK.
Posted Mar 16, 2009 13:45 UTC (Mon) by ikm (subscriber, #493)
> And that's going to help the broken application running on another filesystem exactly how?
It's not. We are talking about fixing problems users start to experience when they switch from ext3 to ext4. None of the other goals, such as fixing all the apps, making all filesystems happy, feeding the hungry and making world a better place are being pursued here. The 2.6.30 fixes do what they are supposed to do, without breaking anything else. So it is a good thing, and I don't understand why you seem to be against it.
Sure, there's lots of stuff which ain't working right, but it's not a subject here. World's not perfect, and it's not going to be any time soon.
Posted Mar 15, 2009 12:57 UTC (Sun) by ikm (subscriber, #493)
Gosh. What people suggest here is that standards should not be used as an excuse for unwanted filesystem behavior.
Posted Mar 16, 2009 0:21 UTC (Mon) by bojan (subscriber, #14302)
(I wonder if we can allow it to write dirty data to disk when under memory
pressure, as well? ;) )
Posted Mar 15, 2009 15:18 UTC (Sun) by dcoutts (guest, #5387)
Posted Mar 15, 2009 12:20 UTC (Sun) by alexl (subscriber, #19068)
Are you crazy? That would break ACID guarantees for all databases, etc.
fsync() is about much more than data-before-metadata.
Posted Mar 15, 2009 21:28 UTC (Sun) by bojan (subscriber, #14302)
Close to it ;-)
I admit, that was a bit tongue-in-cheek, to point out that current ext3 "lock up on fsync" behaviour is total nonsense.
Posted Mar 16, 2009 14:09 UTC (Mon) by ikm (subscriber, #493)
Once I had MySQL running on an XFS filesystem, and the system has hanged for some reason. The database got broken so horribly I had to restore it from backups. I wouldn't really count on any 'ACID guarantees' here :) An UPS and a ventilated dust-free environment is our only ACID guarantee :)
Posted Mar 17, 2009 5:41 UTC (Tue) by efexis (guest, #26355)
Posted Mar 17, 2009 11:59 UTC (Tue) by ikm (subscriber, #493)
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