[PATCH v4 1/2] arm64: Introduce IRQ stack

Pratyush Anand panand at redhat.com
Thu Oct 8 03:25:20 PDT 2015

Hi Jungseok,

On 07/10/2015:03:28:11 PM, Jungseok Lee wrote:
> Currently, kernel context and interrupts are handled using a single
> kernel stack navigated by sp_el1. This forces a system to use 16KB
> stack, not 8KB one. This restriction makes low memory platforms suffer
> from memory pressure accompanied by performance degradation.

How will it behave on 64K Page system? There, it would take atleast 64K per cpu,

> +int alloc_irq_stack(unsigned int cpu)
> +{
> +	void *stack;
> +
> +	if (per_cpu(irq_stacks, cpu).stack)
> +		return 0;
> +
> +	stack = (void *)__get_free_pages(THREADINFO_GFP, THREAD_SIZE_ORDER);

Above would not compile for 64K pages as THREAD_SIZE_ORDER is only defined for
non 64K. This need to be fixed.


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