Re: [PATCH v2 00/13] Dynamic Kernel Stacks

[Pasha Tatashin]

On 04-24 12:41, Dave Hansen wrote:
> On 4/24/26 12:14, David Stevens wrote:
> > The question is then: is this approach something that is fundamentally
> > untenable in the kernel
> 
> Yes. Fundamentally untenable.
> 
> Not allowing stack faults has been a wonderful simplification. It's one
> of those things that just plain makes the kernel easier to maintain.
> Saving low single digits of system memory is not exactly making me eager
> to go back to the harder-to-maintain days.
> 
> I seriously doubt that this 1% is the lowest hanging fruit for memory
> bloat on these systems. ;)

This true until, in a fleet of millions of machines, you encounter a 
one-in-a-billion chance of a stack overflow. You are then forced to 
double the statically allocated kernel stacks on every machine, paying a 
memory tax even though 99.999..% of threads never exceed 4K. This 
overhead accumulates to petabytes of wasted capacity.

Pasha