Re: IO regression after ab8fabd46f on x86 kernels with high memory

[Rik van Riel]

On 04/29/2013 06:03 PM, Linus Torvalds wrote:

> Seriously, you can compile yourself a 64-bit kernel and continue to
> use your 32-bit user-land. And you can complain to whatever distro you
> used that it didn't do that in the first place. But we're not going to
> bother with trying to tune PAE for some particular load. It's just not
> worth it to anybody.

I can think of one way to "tune PAE" that will help
avoid the breakage, and at the same time draw the
attention of users.

Limit the memory that a 32 bit PAE kernel uses, to
something small enough where the user will not
encounter random breakage.  Maybe 8 or 12GB?

It could also print out a friendly message, to
inform the user they should upgrade to a 64 bit
kernel to enjoy the use of all of their memory.

It is a bit of a heavy stick, but I suspect that
it would clue in all of the affected users.

If you have no objection to this, I'll whip up a
patch.

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