linux/kernel/locking/qspinlock_stat.h
Thomas Gleixner c942fddf87 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
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>
2019-05-30 11:26:37 -07:00

143 lines
3.0 KiB
C

/* 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 */