Messages in this thread | | | Date | Mon, 07 Sep 2015 15:33:36 +0100 | From | James Morse <> | Subject | Re: [RFC PATCH 0/3] Implement IRQ stack on ARM64 |
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On 04/09/15 15:23, Jungseok Lee wrote: > ARM64 kernel allocates 16KB kernel stack when creating a process. In case > of low memory platforms with tough workloads on userland, this order-2 > allocation request reaches to memory pressure and performance degradation > simultaenously since VM page allocator falls into slowpath frequently, > which triggers page reclaim and compaction. > > I believe that one of the best solutions is to reduce kernel stack size. > According to the following data from stack tracer with some fixes, [1], > a separate IRQ stack would greatly help to decrease a kernel stack depth. >
Hi Jungseok Lee,
I was working on a similar patch for irq stack, (patch as a follow up email).
I suggest we work together on a single implementation. I think the only major difference is that you're using sp_el0 as a temporary register to store a copy of the stack-pointer to find struct thread_info, whereas I was copying it between stacks (ends up as 2x ldp/stps), which keeps the change restricted to irq_stack setup code.
We should get some feedback as to which approach is preferred.
Thanks,
James Morse
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