c942fddf87
Based on 3 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version [author] [kishon] [vijay] [abraham] [i] [kishon]@[ti] [com] this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version [author] [graeme] [gregory] [gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i] [kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema] [hk] [hemahk]@[ti] [com] this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1105 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
143 lines
3.0 KiB
C
143 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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*
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* Authors: Waiman Long <longman@redhat.com>
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*/
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#include "lock_events.h"
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#ifdef CONFIG_LOCK_EVENT_COUNTS
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#ifdef CONFIG_PARAVIRT_SPINLOCKS
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/*
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* Collect pvqspinlock locking event counts
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*/
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#include <linux/sched.h>
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#include <linux/sched/clock.h>
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#include <linux/fs.h>
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#define EVENT_COUNT(ev) lockevents[LOCKEVENT_ ## ev]
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/*
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* PV specific per-cpu counter
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*/
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static DEFINE_PER_CPU(u64, pv_kick_time);
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/*
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* Function to read and return the PV qspinlock counts.
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*
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* The following counters are handled specially:
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* 1. pv_latency_kick
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* Average kick latency (ns) = pv_latency_kick/pv_kick_unlock
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* 2. pv_latency_wake
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* Average wake latency (ns) = pv_latency_wake/pv_kick_wake
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* 3. pv_hash_hops
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* Average hops/hash = pv_hash_hops/pv_kick_unlock
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*/
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ssize_t lockevent_read(struct file *file, char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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char buf[64];
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int cpu, id, len;
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u64 sum = 0, kicks = 0;
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/*
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* Get the counter ID stored in file->f_inode->i_private
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*/
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id = (long)file_inode(file)->i_private;
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if (id >= lockevent_num)
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return -EBADF;
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for_each_possible_cpu(cpu) {
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sum += per_cpu(lockevents[id], cpu);
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/*
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* Need to sum additional counters for some of them
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*/
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switch (id) {
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case LOCKEVENT_pv_latency_kick:
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case LOCKEVENT_pv_hash_hops:
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kicks += per_cpu(EVENT_COUNT(pv_kick_unlock), cpu);
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break;
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case LOCKEVENT_pv_latency_wake:
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kicks += per_cpu(EVENT_COUNT(pv_kick_wake), cpu);
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break;
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}
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}
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if (id == LOCKEVENT_pv_hash_hops) {
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u64 frac = 0;
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if (kicks) {
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frac = 100ULL * do_div(sum, kicks);
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frac = DIV_ROUND_CLOSEST_ULL(frac, kicks);
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}
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/*
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* Return a X.XX decimal number
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*/
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len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n",
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sum, frac);
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} else {
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/*
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* Round to the nearest ns
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*/
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if ((id == LOCKEVENT_pv_latency_kick) ||
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(id == LOCKEVENT_pv_latency_wake)) {
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if (kicks)
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sum = DIV_ROUND_CLOSEST_ULL(sum, kicks);
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}
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len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum);
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}
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return simple_read_from_buffer(user_buf, count, ppos, buf, len);
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}
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/*
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* PV hash hop count
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*/
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static inline void lockevent_pv_hop(int hopcnt)
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{
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this_cpu_add(EVENT_COUNT(pv_hash_hops), hopcnt);
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}
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/*
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* Replacement function for pv_kick()
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*/
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static inline void __pv_kick(int cpu)
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{
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u64 start = sched_clock();
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per_cpu(pv_kick_time, cpu) = start;
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pv_kick(cpu);
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this_cpu_add(EVENT_COUNT(pv_latency_kick), sched_clock() - start);
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}
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/*
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* Replacement function for pv_wait()
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*/
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static inline void __pv_wait(u8 *ptr, u8 val)
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{
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u64 *pkick_time = this_cpu_ptr(&pv_kick_time);
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*pkick_time = 0;
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pv_wait(ptr, val);
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if (*pkick_time) {
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this_cpu_add(EVENT_COUNT(pv_latency_wake),
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sched_clock() - *pkick_time);
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lockevent_inc(pv_kick_wake);
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}
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}
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#define pv_kick(c) __pv_kick(c)
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#define pv_wait(p, v) __pv_wait(p, v)
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#endif /* CONFIG_PARAVIRT_SPINLOCKS */
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#else /* CONFIG_LOCK_EVENT_COUNTS */
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static inline void lockevent_pv_hop(int hopcnt) { }
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#endif /* CONFIG_LOCK_EVENT_COUNTS */
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