On Fri, Oct 09, 2020 at 07:45:54PM +0200, Peter Zijlstra wrote: > +DEFINE_STATIC_KEY_TRUE(irq_preemption_key); > + > +/* > + * SC:cond_resched > + * SC:might_resched > + * SC:preempt_schedule > + * SC:preempt_schedule_notrace > + * SB:irq_preemption_key > + * > + * > + * ZERO > + * cond_resched <- RET0 > + * might_resched <- NOP > + * preempt_schedule <- NOP > + * preempt_schedule_notrace <- NOP > + * irq_preemption_key <- false > + * > + * NONE: > + * cond_resched <- __cond_resched > + * might_resched <- NOP > + * preempt_schedule <- NOP > + * preempt_schedule_notrace <- NOP > + * irq_preemption_key <- false > + * > + * VOLUNTARY: > + * cond_resched <- __cond_resched > + * might_resched <- __might_resched > + * preempt_schedule <- NOP > + * preempt_schedule_notrace <- NOP > + * irq_preemption_key <- false > + * > + * FULL: > + * cond_resched <- RET0 > + * might_resched <- NOP > + * preempt_schedule <- preempt_schedule > + * preempt_schedule_notrace <- preempt_schedule_notrace > + * irq_preemption_key <- true > + */
That's cute! I'll try to end up to that result. > +static int __init setup_preempt_mode(char *str) > +{ > + if (!strcmp(str, "zero")) { > + static_call_update(cond_resched, __static_call_return0); > + static_call_update(might_resched, (void (*)(void))NULL); > + static_call_update(preempt_schedule, (void (*)(void))NULL); > + static_call_update(preempt_schedule_notrace, (void > (*)(void))NULL); > + static_branch_disable(&irq_preemption_key); > + printk("XXX PREEMPT: %s\n", str); > + } else if (!strcmp(str, "none")) { > + static_call_update(cond_resched, __cond_resched); > + static_call_update(might_resched, (void (*)(void))NULL); > + static_call_update(preempt_schedule, (void (*)(void))NULL); > + static_call_update(preempt_schedule_notrace, (void > (*)(void))NULL); > + static_branch_disable(&irq_preemption_key); > + printk("XXX PREEMPT: %s\n", str); > + } else if (!strcmp(str, "voluntary")) { > + static_call_update(cond_resched, __cond_resched); > + static_call_update(might_resched, __might_resched); > + static_call_update(preempt_schedule, (void (*)(void))NULL); > + static_call_update(preempt_schedule_notrace, (void > (*)(void))NULL); > + static_branch_disable(&irq_preemption_key); > + printk("XXX PREEMPT: %s\n", str); > + } else if (!strcmp(str, "ponies")) { > + static_call_update(cond_resched, __cond_resched); > + static_call_update(might_resched, (void (*)(void))NULL); > + static_call_update(preempt_schedule, preempt_schedule_thunk); > + static_call_update(preempt_schedule_notrace, > preempt_schedule_notrace_thunk); > + static_branch_enable(&irq_preemption_key); > + printk("XXX PREEMPT: %s\n", str); Why would we need that ponies version? Thanks!