/* SPDX-License-Identifier: GPL-2.0-or-later *//* * * Authors: Waiman Long <longman@redhat.com> */ #include "lock_events.h" #ifdef CONFIG_LOCK_EVENT_COUNTS#ifdef CONFIG_PARAVIRT_SPINLOCKS/* * Collect pvqspinlock locking event counts */#include <linux/sched.h>#include <linux/sched/clock.h>#include <linux/fs.h> #define EVENT_COUNT(ev)	lockevents[LOCKEVENT_ ## ev] /* * PV specific per-cpu counter */static DEFINE_PER_CPU(u64, pv_kick_time); /* * Function to read and return the PV qspinlock counts. * * The following counters are handled specially: * 1. pv_latency_kick *    Average kick latency (ns) = pv_latency_kick/pv_kick_unlock * 2. pv_latency_wake *    Average wake latency (ns) = pv_latency_wake/pv_kick_wake * 3. pv_hash_hops *    Average hops/hash = pv_hash_hops/pv_kick_unlock */ssize_t lockevent_read(struct file *file, char __user *user_buf,		       size_t count, loff_t *ppos){	char buf[64];	int cpu, id, len;	u64 sum = 0, kicks = 0; 	/*	 * Get the counter ID stored in file->f_inode->i_private	 */	id = (long)file_inode(file)->i_private; 	if (id >= lockevent_num)		return -EBADF; 	for_each_possible_cpu(cpu) {		sum += per_cpu(lockevents[id], cpu);		/*		 * Need to sum additional counters for some of them		 */		switch (id) { 		case LOCKEVENT_pv_latency_kick:		case LOCKEVENT_pv_hash_hops:			kicks += per_cpu(EVENT_COUNT(pv_kick_unlock), cpu);			break; 		case LOCKEVENT_pv_latency_wake:			kicks += per_cpu(EVENT_COUNT(pv_kick_wake), cpu);			break;		}	} 	if (id == LOCKEVENT_pv_hash_hops) {		u64 frac = 0; 		if (kicks) {			frac = 100ULL * do_div(sum, kicks);			frac = DIV_ROUND_CLOSEST_ULL(frac, kicks);		} 		/*		 * Return a X.XX decimal number		 */		len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n",			       sum, frac);	} else {		/*		 * Round to the nearest ns		 */		if ((id == LOCKEVENT_pv_latency_kick) ||		    (id == LOCKEVENT_pv_latency_wake)) {			if (kicks)				sum = DIV_ROUND_CLOSEST_ULL(sum, kicks);		}		len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum);	} 	return simple_read_from_buffer(user_buf, count, ppos, buf, len);} /* * PV hash hop count */static inline void lockevent_pv_hop(int hopcnt){	this_cpu_add(EVENT_COUNT(pv_hash_hops), hopcnt);} /* * Replacement function for pv_kick() */static inline void __pv_kick(int cpu){	u64 start = sched_clock(); 	per_cpu(pv_kick_time, cpu) = start;	pv_kick(cpu);	this_cpu_add(EVENT_COUNT(pv_latency_kick), sched_clock() - start);} /* * Replacement function for pv_wait() */static inline void __pv_wait(u8 *ptr, u8 val){	u64 *pkick_time = this_cpu_ptr(&pv_kick_time); 	*pkick_time = 0;	pv_wait(ptr, val);	if (*pkick_time) {		this_cpu_add(EVENT_COUNT(pv_latency_wake),			     sched_clock() - *pkick_time);		lockevent_inc(pv_kick_wake);	}} #define pv_kick(c)	__pv_kick(c)#define pv_wait(p, v)	__pv_wait(p, v) #endif /* CONFIG_PARAVIRT_SPINLOCKS */ #else /* CONFIG_LOCK_EVENT_COUNTS */ static inline void lockevent_pv_hop(int hopcnt)	{ } #endif /* CONFIG_LOCK_EVENT_COUNTS */