On 2025-01-06 10:49:19 [+0530], Shrikanth Hegde wrote:
> --- a/arch/powerpc/kernel/interrupt.c
> +++ b/arch/powerpc/kernel/interrupt.c
> @@ -25,6 +25,10 @@
> unsigned long global_dbcr0[NR_CPUS];
> #endif
>
> +#if defined(CONFIG_PREEMPT_DYNAMIC) &&
> defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
> +DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
> +#endif
I am uncertain here: Do you need to DEFINE it? It is set by the sched
core which also defines it. It should be same thing after all, right?
> +
> #ifdef CONFIG_PPC_BOOK3S_64
> DEFINE_STATIC_KEY_FALSE(interrupt_exit_not_reentrant);
> static inline bool exit_must_hard_disable(void)
> @@ -396,7 +400,7 @@ notrace unsigned long
> interrupt_exit_kernel_prepare(struct pt_regs *regs)
> /* Returning to a kernel context with local irqs enabled. */
> WARN_ON_ONCE(!(regs->msr & MSR_EE));
> again:
> - if (IS_ENABLED(CONFIG_PREEMPTION)) {
> + if (preempt_model_preemptible()) {
CONFIG_HAVE_PREEMPT_DYNAMIC_KEY is the only option, right? Wouldn't
| #DEFINE need_irq_preemption() \
| (static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
|
| if (need_irq_preemption()) {
be a bit smaller/ quicker? This could be a fast path ;)
> /* Return to preemptible kernel context */
> if (unlikely(read_thread_flags() & _TIF_NEED_RESCHED)) {
> if (preempt_count() == 0)
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index edf5cabe5dfd..2556fa8ec019 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -266,7 +266,11 @@ static int __die(const char *str, struct pt_regs *regs,
> long err)
> printk("%s PAGE_SIZE=%luK%s%s%s%s%s%s %s\n",
> IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? "LE" : "BE",
> PAGE_SIZE / 1024, get_mmu_str(),
> - IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
> + preempt_model_none() ? "none" :
> + preempt_model_voluntary() ? "voluntary" :
> + preempt_model_full() ? "full" :
> + preempt_model_lazy() ? "lazy" :
> + "",
So intend to rework this part. I have patches stashed at
https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/staging.git/log/?h=preemption_string
which I didn't sent yet due to the merge window. Just a heads up ;)
> IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
> IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" __stringify(NR_CPUS)) : "",
> debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
Sebastian
