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sched: Add /debug/sched_preempt
Add a debugfs file to muck about with the preempt mode at runtime. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/YAsGiUYf6NyaTplX@hirez.programming.kicks-ass.net
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1 changed files with 126 additions and 9 deletions
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@ -5363,37 +5363,154 @@ EXPORT_STATIC_CALL(preempt_schedule_notrace);
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* preempt_schedule_notrace <- preempt_schedule_notrace
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* preempt_schedule_notrace <- preempt_schedule_notrace
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* irqentry_exit_cond_resched <- irqentry_exit_cond_resched
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* irqentry_exit_cond_resched <- irqentry_exit_cond_resched
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*/
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*/
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static int __init setup_preempt_mode(char *str)
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enum {
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preempt_dynamic_none = 0,
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preempt_dynamic_voluntary,
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preempt_dynamic_full,
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};
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static int preempt_dynamic_mode = preempt_dynamic_full;
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static int sched_dynamic_mode(const char *str)
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{
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{
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if (!strcmp(str, "none")) {
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if (!strcmp(str, "none"))
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return 0;
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if (!strcmp(str, "voluntary"))
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return 1;
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if (!strcmp(str, "full"))
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return 2;
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return -1;
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}
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static void sched_dynamic_update(int mode)
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{
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/*
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* Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in
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* the ZERO state, which is invalid.
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*/
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static_call_update(cond_resched, __cond_resched);
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static_call_update(might_resched, __cond_resched);
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static_call_update(preempt_schedule, __preempt_schedule_func);
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static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
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static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
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switch (mode) {
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case preempt_dynamic_none:
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static_call_update(cond_resched, __cond_resched);
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static_call_update(cond_resched, __cond_resched);
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static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
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static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
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static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
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static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
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static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
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static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
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static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
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static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
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pr_info("Dynamic Preempt: %s\n", str);
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pr_info("Dynamic Preempt: none\n");
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} else if (!strcmp(str, "voluntary")) {
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break;
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case preempt_dynamic_voluntary:
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static_call_update(cond_resched, __cond_resched);
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static_call_update(cond_resched, __cond_resched);
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static_call_update(might_resched, __cond_resched);
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static_call_update(might_resched, __cond_resched);
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static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
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static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
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static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
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static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
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static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
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static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
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pr_info("Dynamic Preempt: %s\n", str);
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pr_info("Dynamic Preempt: voluntary\n");
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} else if (!strcmp(str, "full")) {
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break;
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case preempt_dynamic_full:
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static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0);
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static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0);
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static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
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static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
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static_call_update(preempt_schedule, __preempt_schedule_func);
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static_call_update(preempt_schedule, __preempt_schedule_func);
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static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
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static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
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static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
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static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
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pr_info("Dynamic Preempt: %s\n", str);
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pr_info("Dynamic Preempt: full\n");
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} else {
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break;
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pr_warn("Dynamic Preempt: Unsupported preempt mode %s, default to full\n", str);
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}
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preempt_dynamic_mode = mode;
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}
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static int __init setup_preempt_mode(char *str)
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{
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int mode = sched_dynamic_mode(str);
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if (mode < 0) {
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pr_warn("Dynamic Preempt: unsupported mode: %s\n", str);
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return 1;
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return 1;
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}
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}
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sched_dynamic_update(mode);
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return 0;
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return 0;
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}
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}
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__setup("preempt=", setup_preempt_mode);
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__setup("preempt=", setup_preempt_mode);
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#ifdef CONFIG_SCHED_DEBUG
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static ssize_t sched_dynamic_write(struct file *filp, const char __user *ubuf,
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size_t cnt, loff_t *ppos)
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{
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char buf[16];
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int mode;
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if (cnt > 15)
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cnt = 15;
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if (copy_from_user(&buf, ubuf, cnt))
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return -EFAULT;
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buf[cnt] = 0;
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mode = sched_dynamic_mode(strstrip(buf));
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if (mode < 0)
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return mode;
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sched_dynamic_update(mode);
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*ppos += cnt;
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return cnt;
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}
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static int sched_dynamic_show(struct seq_file *m, void *v)
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{
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static const char * preempt_modes[] = {
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"none", "voluntary", "full"
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};
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int i;
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for (i = 0; i < ARRAY_SIZE(preempt_modes); i++) {
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if (preempt_dynamic_mode == i)
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seq_puts(m, "(");
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seq_puts(m, preempt_modes[i]);
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if (preempt_dynamic_mode == i)
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seq_puts(m, ")");
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seq_puts(m, " ");
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}
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seq_puts(m, "\n");
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return 0;
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}
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static int sched_dynamic_open(struct inode *inode, struct file *filp)
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{
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return single_open(filp, sched_dynamic_show, NULL);
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}
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static const struct file_operations sched_dynamic_fops = {
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.open = sched_dynamic_open,
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.write = sched_dynamic_write,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static __init int sched_init_debug_dynamic(void)
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{
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debugfs_create_file("sched_preempt", 0644, NULL, NULL, &sched_dynamic_fops);
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return 0;
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}
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late_initcall(sched_init_debug_dynamic);
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#endif /* CONFIG_SCHED_DEBUG */
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#endif /* CONFIG_PREEMPT_DYNAMIC */
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#endif /* CONFIG_PREEMPT_DYNAMIC */
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