LXR linux/tools/virtio/ringtest/main.h

   1/*
   2 * Copyright (C) 2016 Red Hat, Inc.
   3 * Author: Michael S. Tsirkin <mst@redhat.com>
   4 * This work is licensed under the terms of the GNU GPL, version 2.
   5 *
   6 * Common macros and functions for ring benchmarking.
   7 */
   8#ifndef MAIN_H
   9#define MAIN_H
  10
  11#include <stdbool.h>
  12
  13extern bool do_exit;
  14
  15#if defined(__x86_64__) || defined(__i386__)
  16#include "x86intrin.h"
  17
  18static inline void wait_cycles(unsigned long long cycles)
  19{
  20        unsigned long long t;
  21
  22        t = __rdtsc();
  23        while (__rdtsc() - t < cycles) {}
  24}
  25
  26#define VMEXIT_CYCLES 500
  27#define VMENTRY_CYCLES 500
  28
  29#else
  30static inline void wait_cycles(unsigned long long cycles)
  31{
  32        _Exit(5);
  33}
  34#define VMEXIT_CYCLES 0
  35#define VMENTRY_CYCLES 0
  36#endif
  37
  38static inline void vmexit(void)
  39{
  40        if (!do_exit)
  41                return;
  42        
  43        wait_cycles(VMEXIT_CYCLES);
  44}
  45static inline void vmentry(void)
  46{
  47        if (!do_exit)
  48                return;
  49        
  50        wait_cycles(VMENTRY_CYCLES);
  51}
  52
  53/* implemented by ring */
  54void alloc_ring(void);
  55/* guest side */
  56int add_inbuf(unsigned, void *, void *);
  57void *get_buf(unsigned *, void **);
  58void disable_call();
  59bool enable_call();
  60void kick_available();
  61void poll_used();
  62/* host side */
  63void disable_kick();
  64bool enable_kick();
  65bool use_buf(unsigned *, void **);
  66void call_used();
  67void poll_avail();
  68
  69/* implemented by main */
  70extern bool do_sleep;
  71void kick(void);
  72void wait_for_kick(void);
  73void call(void);
  74void wait_for_call(void);
  75
  76extern unsigned ring_size;
  77
  78/* Compiler barrier - similar to what Linux uses */
  79#define barrier() asm volatile("" ::: "memory")
  80
  81/* Is there a portable way to do this? */
  82#if defined(__x86_64__) || defined(__i386__)
  83#define cpu_relax() asm ("rep; nop" ::: "memory")
  84#else
  85#define cpu_relax() assert(0)
  86#endif
  87
  88extern bool do_relax;
  89
  90static inline void busy_wait(void)
  91{
  92        if (do_relax)
  93                cpu_relax();
  94        else
  95                /* prevent compiler from removing busy loops */
  96                barrier();
  97} 
  98
  99/*
 100 * Not using __ATOMIC_SEQ_CST since gcc docs say they are only synchronized
 101 * with other __ATOMIC_SEQ_CST calls.
 102 */
 103#define smp_mb() __sync_synchronize()
 104
 105/*
 106 * This abuses the atomic builtins for thread fences, and
 107 * adds a compiler barrier.
 108 */
 109#define smp_release() do { \
 110    barrier(); \
 111    __atomic_thread_fence(__ATOMIC_RELEASE); \
 112} while (0)
 113
 114#define smp_acquire() do { \
 115    __atomic_thread_fence(__ATOMIC_ACQUIRE); \
 116    barrier(); \
 117} while (0)
 118
 119#endif
 120