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JPz
n00b
Joined: 30 Jun 2002
Posts: 23
Location: Clermont-Ferrand, France
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 Posted: Wed Sep 04, 2002 6:57 pm Post subject: Kernel compiled with GCC 3.x |
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Hi,
I have seen some reports from a XFS user that there have been problems with kernels compiled with GCC 3.x. In fact, there seem to be a problem with *any* application making use of O_DIRECT while doing I/O. O_DIRECT allows skipping the VM for I/O operations.
XFS for instance makes an intensive use of O_DIRECT. ReiserFS seems to do that too. In fact any filesystem can have the problem and database servers are the perfect kind of application that can be affected as it uses O_DIRECT too. The symptoms seem to be corrupted filesystems, wrong file sizes and so on. An exception seems to be on ext3 which is apparently not implementing the O_DIRECT flag.
I have been quite afraid of this, beeing interessted by XFS and GCC 3.2-based systems  By searching on the mailing-list archives, I have found some related things.
I haven't experimented this msyself as I'm still using GCC 2.95.3 (which doesn't have the problem) but it is likely that there is a problem here. I wouldn't like to get a corrupted FS on my working machines ...
Does anyone know more about that ? I'd like to hear many points of view on this.
Thanks a lot. |
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rac
Bodhisattva
Joined: 30 May 2002
Posts: 6553
Location: Japanifornia
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| Posted: Wed Sep 04, 2002 7:44 pm Post subject: |
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I have been using XFS with a GCC 3.1-compiled kernel (stock 2.4.18+SGI XFS 1.1 patches) on both an original Athlon and an original K6 for 3 months with no problems, but not on a database server.
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For every higher wall, there is a taller ladder |
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JPz
n00b
Joined: 30 Jun 2002
Posts: 23
Location: Clermont-Ferrand, France
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| Posted: Wed Sep 04, 2002 7:52 pm Post subject: |
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Actually this is not database related. The problem has happened on 'classic' workstations that you would use for your day-to-day work. Simply this tend to appear faster on XFS because XFS makes an intensive use of O_DIRECT, notably in the defrag code.
So I repeat, I have never seen that myself, but this is something that get me afraid. I will try to find the test program that shows the problems and report it here. |
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JPz
n00b
Joined: 30 Jun 2002
Posts: 23
Location: Clermont-Ferrand, France
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