Messages in this thread | | | Date | Mon, 29 Apr 2013 18:06:19 -0700 | From | "Pierre-Loup A. Griffais" <> | Subject | Re: IO regression after ab8fabd46f on x86 kernels with high memory |
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On 04/29/2013 05:48 PM, Rik van Riel wrote: > 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. >
That would be pretty useful, especially if I can then convince distributors to apply it and roll it out ASAP. I haven't personally observed any problems with mem=15G whereas mem=16G exhibits the IO issue upfront and more than that exhibits the OOM-killer / low memory starvation issue that existed before Johannes change.
Thanks, - Pierre-Loup
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