Messages in this thread | | | Subject | Re: [13/18] x86_64: Allow fallback for the stack | From | Peter Zijlstra <> | Date | Thu, 04 Oct 2007 14:08:12 +0200 |
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On Thu, 2007-10-04 at 13:56 +0200, Andi Kleen wrote: > On Thursday 04 October 2007 05:59:48 Christoph Lameter wrote: > > Peter Zijlstra has recently demonstrated that we can have order 1 allocation > > failures under memory pressure with small memory configurations. The > > x86_64 stack has a size of 8k and thus requires a order 1 allocation. > > We've known for ages that it is possible. But it has been always so rare > that it was ignored. > > Is there any evidence this is more common now than it used to be?
The order-1 allocation failures where GFP_ATOMIC, because SLUB uses !0 order for everything. Kernel stack allocation is GFP_KERNEL I presume. Also, I use 4k stacks on all my machines.
Maybe the cpumask thing needs an extended api, one that falls back to kmalloc if NR_CPUS >> sane.
That way that cannot be an argument to inflate stacks.
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