[2.6 patch] let 4KSTACKS depend on EXPERIMENTAL and XFS on 4KSTACKS=n

From: Adrian Bunk (bunk_at_fs.tum.de)
Date: 07/20/04

  • Next message: Geert Uytterhoeven: "[PATCH] depends on PCI: Multi-Tech, SyncLink, Applicom serial" 
    Date:	Tue, 20 Jul 2004 21:50:12 +0200
To: "Jeffrey E. Hundstad" <jeffrey.hundstad@mnsu.edu>, Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>, Steve Lord <lord@xfs.org>

    On Tue, Jul 20, 2004 at 09:39:21AM -0500, Jeffrey E. Hundstad wrote:
    > Steve Lord wrote:
    >
    > >Don't use 4K stacks and XFS. What you hit here is a path where the
    > >filesystem is getting full and it needs to free some reserved space
    > >by flushing cached data which is using reserved extents. Reserved
    > >extents do not yet have an on disk address and they include a
    > >reservation for the worst case metadata usage. Flushing them will
    > >get you room back.
    > >
    > >As you can see, it is a pretty deep call stack, most of XFS is going
    > >to work just fine with a 4K stack, but there are end cases like
    > >this one which will just not fit.
    >
    >
    > If this is a known truth with XFS maybe it would be a good idea to have
    > 4K stacks and XFS be an impossible combination using the config tool.

    The patch below does:

    1. let 4KSTACKS depend on EXPERIMENTAL
    Rationale:
    4Kb stacks on i386 are the future. But currently this option might still
    cause problems in some areas of the kernel. OTOH, 4Kb stacks isn't a big
    gain for most people.
    2.6 is a stable kernel series, and 4KSTACKS=n is the safe choice.
    Once all issues with 4KSTACKS=y are resolved this can be reverted.

    2. let XFS depend on (4KSTACKS=n || BROKEN)
    Rationale:
    Mark Loy said:
      Don't use 4K stacks and XFS.
    Mark this combination as BROKEN until XFS is fixed.
    This might result in XFS support disappearing for some people, but if
    they use EXPERIMENTAL=y they should know what they are doing.

    The 4KSTACKS option has to be moved for that it's asked before XFS in
    "make config".

    diffstat output:
     arch/i386/Kconfig | 19 ++++++++++---------
     fs/Kconfig | 1 +
     2 files changed, 11 insertions(+), 9 deletions(-)

    Signed-off-by: Adrian Bunk <bunk@fs.tum.de>

    --- linux-2.6.8-rc2-full/arch/i386/Kconfig.old 2004-07-20 21:00:32.000000000 +0200
    +++ linux-2.6.8-rc2-full/arch/i386/Kconfig 2004-07-20 21:03:30.000000000 +0200
    @@ -865,6 +865,16 @@
             generate incorrect output with certain kernel constructs when
             -mregparm=3 is used.
     
    +config 4KSTACKS
    + bool "Use 4Kb for kernel stacks instead of 8Kb"
    + depends on EXPERIMENTAL
    + help
    + If you say Y here the kernel will use a 4Kb stacksize for the
    + kernel stack attached to each process/thread. This facilitates
    + running more threads on a system and also reduces the pressure
    + on the VM subsystem for higher order allocations. This option
    + will also use IRQ stacks to compensate for the reduced stackspace.
    +
     endmenu
     
     
    @@ -1289,15 +1299,6 @@
               If you don't debug the kernel, you can say N, but we may not be able
               to solve problems without frame pointers.
     
    -config 4KSTACKS
    - bool "Use 4Kb for kernel stacks instead of 8Kb"
    - help
    - If you say Y here the kernel will use a 4Kb stacksize for the
    - kernel stack attached to each process/thread. This facilitates
    - running more threads on a system and also reduces the pressure
    - on the VM subsystem for higher order allocations. This option
    - will also use IRQ stacks to compensate for the reduced stackspace.
    -
     config X86_FIND_SMP_CONFIG
             bool
             depends on X86_LOCAL_APIC || X86_VOYAGER
    --- linux-2.6.8-rc2-full/fs/Kconfig.old 2004-07-20 21:04:02.000000000 +0200
    +++ linux-2.6.8-rc2-full/fs/Kconfig 2004-07-20 21:04:25.000000000 +0200
    @@ -294,6 +294,7 @@
     
     config XFS_FS
             tristate "XFS filesystem support"
    + depends on (4KSTACKS=n || BROKEN)
             help
               XFS is a high performance journaling filesystem which originated
               on the SGI IRIX platform. It is completely multi-threaded, can
    -
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