| Michael S. Tsirkin | 481eaec | 2016-01-21 14:44:10 +0200 | [diff] [blame] | 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 | |
| 13 | extern bool do_exit; |
| 14 | |
| 15 | #if defined(__x86_64__) || defined(__i386__) |
| 16 | #include "x86intrin.h" |
| 17 | |
| 18 | static 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 |
| 30 | static 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 | |
| 38 | static inline void vmexit(void) |
| 39 | { |
| 40 | if (!do_exit) |
| 41 | return; |
| 42 | |
| 43 | wait_cycles(VMEXIT_CYCLES); |
| 44 | } |
| 45 | static inline void vmentry(void) |
| 46 | { |
| 47 | if (!do_exit) |
| 48 | return; |
| 49 | |
| 50 | wait_cycles(VMENTRY_CYCLES); |
| 51 | } |
| 52 | |
| 53 | /* implemented by ring */ |
| 54 | void alloc_ring(void); |
| 55 | /* guest side */ |
| 56 | int add_inbuf(unsigned, void *, void *); |
| 57 | void *get_buf(unsigned *, void **); |
| 58 | void disable_call(); |
| 59 | bool enable_call(); |
| 60 | void kick_available(); |
| 61 | void poll_used(); |
| 62 | /* host side */ |
| 63 | void disable_kick(); |
| 64 | bool enable_kick(); |
| 65 | bool use_buf(unsigned *, void **); |
| 66 | void call_used(); |
| 67 | void poll_avail(); |
| 68 | |
| 69 | /* implemented by main */ |
| 70 | extern bool do_sleep; |
| 71 | void kick(void); |
| 72 | void wait_for_kick(void); |
| 73 | void call(void); |
| 74 | void wait_for_call(void); |
| 75 | |
| 76 | extern 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 | |
| 88 | extern bool do_relax; |
| 89 | |
| 90 | static 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 |