1 | // |
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2 | // Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo |
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3 | // |
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4 | // The contents of this file are covered under the licence agreement in the |
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5 | // file "LICENCE" distributed with Cforall. |
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6 | // |
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7 | // kernel_private.hfa -- |
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8 | // |
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9 | // Author : Thierry Delisle |
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10 | // Created On : Mon Feb 13 12:27:26 2017 |
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11 | // Last Modified By : Peter A. Buhr |
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12 | // Last Modified On : Wed Aug 12 08:21:33 2020 |
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13 | // Update Count : 9 |
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14 | // |
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15 | |
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16 | #pragma once |
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17 | |
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18 | #if !defined(__cforall_thread__) |
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19 | #error kernel_private.hfa should only be included in libcfathread source |
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20 | #endif |
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21 | |
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22 | #include "kernel.hfa" |
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23 | #include "thread.hfa" |
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24 | |
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25 | #include "alarm.hfa" |
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26 | #include "stats.hfa" |
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27 | |
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28 | extern "C" { |
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29 | #if defined(CFA_HAVE_LINUX_LIBRSEQ) |
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30 | #include <rseq/rseq.h> |
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31 | #elif defined(CFA_HAVE_LINUX_RSEQ_H) |
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32 | #include <linux/rseq.h> |
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33 | #else |
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34 | #ifndef _GNU_SOURCE |
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35 | #error kernel_private requires gnu_source |
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36 | #endif |
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37 | #include <sched.h> |
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38 | #endif |
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39 | } |
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40 | |
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41 | // Defines whether or not we *want* to use io_uring_enter as the idle_sleep blocking call |
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42 | #define CFA_WANT_IO_URING_IDLE |
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43 | |
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44 | // Defines whether or not we *can* use io_uring_enter as the idle_sleep blocking call |
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45 | #if defined(CFA_WANT_IO_URING_IDLE) && defined(CFA_HAVE_LINUX_IO_URING_H) |
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46 | #if defined(CFA_HAVE_IORING_OP_READ) || (defined(CFA_HAVE_READV) && defined(CFA_HAVE_IORING_OP_READV)) |
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47 | #define CFA_WITH_IO_URING_IDLE |
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48 | #endif |
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49 | #endif |
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50 | |
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51 | //----------------------------------------------------------------------------- |
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52 | // Scheduler |
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53 | extern "C" { |
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54 | void disable_interrupts() OPTIONAL_THREAD; |
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55 | void enable_interrupts( bool poll = true ); |
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56 | } |
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57 | |
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58 | void schedule_thread$( thread$ *, unpark_hint hint ) __attribute__((nonnull (1))); |
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59 | |
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60 | extern bool __preemption_enabled(); |
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61 | |
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62 | enum { |
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63 | PREEMPT_NORMAL = 0, |
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64 | PREEMPT_TERMINATE = 1, |
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65 | PREEMPT_IO = 2, |
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66 | }; |
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67 | |
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68 | static inline void __disable_interrupts_checked() { |
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69 | /* paranoid */ verify( __preemption_enabled() ); |
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70 | disable_interrupts(); |
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71 | /* paranoid */ verify( ! __preemption_enabled() ); |
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72 | } |
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73 | |
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74 | static inline void __enable_interrupts_checked( bool poll = true ) { |
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75 | /* paranoid */ verify( ! __preemption_enabled() ); |
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76 | enable_interrupts( poll ); |
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77 | /* paranoid */ verify( __preemption_enabled() ); |
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78 | } |
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79 | |
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80 | //release/wake-up the following resources |
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81 | void __thread_finish( thread$ * thrd ); |
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82 | |
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83 | //----------------------------------------------------------------------------- |
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84 | // Hardware |
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85 | |
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86 | #if defined(CFA_HAVE_LINUX_LIBRSEQ) |
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87 | // No data needed |
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88 | #elif defined(CFA_HAVE_LINUX_RSEQ_H) |
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89 | extern "Cforall" { |
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90 | extern __attribute__((aligned(128))) thread_local volatile struct rseq __cfaabi_rseq; |
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91 | } |
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92 | #else |
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93 | // No data needed |
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94 | #endif |
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95 | |
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96 | static inline int __kernel_getcpu() { |
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97 | /* paranoid */ verify( ! __preemption_enabled() ); |
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98 | #if defined(CFA_HAVE_LINUX_LIBRSEQ) |
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99 | return rseq_current_cpu(); |
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100 | #elif defined(CFA_HAVE_LINUX_RSEQ_H) |
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101 | int r = __cfaabi_rseq.cpu_id; |
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102 | /* paranoid */ verify( r >= 0 ); |
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103 | return r; |
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104 | #else |
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105 | return sched_getcpu(); |
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106 | #endif |
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107 | } |
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108 | |
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109 | //----------------------------------------------------------------------------- |
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110 | // Processor |
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111 | void main(processorCtx_t *); |
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112 | |
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113 | void * __create_pthread( pthread_t *, void * (*)(void *), void * ); |
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114 | void __destroy_pthread( pthread_t pthread, void * stack, void ** retval ); |
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115 | |
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116 | extern cluster * mainCluster; |
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117 | |
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118 | //----------------------------------------------------------------------------- |
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119 | // Threads |
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120 | extern "C" { |
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121 | void __cfactx_invoke_thread(void (*main)(void *), void * this); |
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122 | } |
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123 | |
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124 | __cfaabi_dbg_debug_do( |
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125 | extern void __cfaabi_dbg_thread_register ( thread$ * thrd ); |
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126 | extern void __cfaabi_dbg_thread_unregister( thread$ * thrd ); |
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127 | ) |
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128 | |
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129 | #define TICKET_BLOCKED (-1) // thread is blocked |
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130 | #define TICKET_RUNNING ( 0) // thread is running |
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131 | #define TICKET_UNBLOCK ( 1) // thread should ignore next block |
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132 | |
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133 | //----------------------------------------------------------------------------- |
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134 | // Utils |
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135 | void doregister( struct cluster * cltr, struct thread$ & thrd ); |
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136 | void unregister( struct cluster * cltr, struct thread$ & thrd ); |
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137 | |
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138 | //----------------------------------------------------------------------------- |
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139 | // I/O |
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140 | $io_arbiter * create(void); |
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141 | void destroy($io_arbiter *); |
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142 | |
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143 | //======================================================================= |
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144 | // Cluster lock API |
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145 | //======================================================================= |
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146 | // Lock-Free registering/unregistering of threads |
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147 | // Register a processor to a given cluster and get its unique id in return |
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148 | unsigned register_proc_id( void ); |
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149 | |
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150 | // Unregister a processor from a given cluster using its id, getting back the original pointer |
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151 | void unregister_proc_id( unsigned ); |
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152 | |
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153 | //======================================================================= |
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154 | // Reader-writer lock implementation |
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155 | // Concurrent with doregister/unregister, |
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156 | // i.e., threads can be added at any point during or between the entry/exit |
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157 | |
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158 | //----------------------------------------------------------------------- |
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159 | // simple spinlock underlying the RWLock |
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160 | // Blocking acquire |
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161 | static inline void __atomic_acquire(volatile bool * ll) { |
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162 | while( __builtin_expect(__atomic_exchange_n(ll, (bool)true, __ATOMIC_SEQ_CST), false) ) { |
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163 | while(__atomic_load_n(ll, (int)__ATOMIC_RELAXED)) |
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164 | Pause(); |
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165 | } |
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166 | /* paranoid */ verify(*ll); |
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167 | } |
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168 | |
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169 | // Non-Blocking acquire |
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170 | static inline bool __atomic_try_acquire(volatile bool * ll) { |
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171 | return !__atomic_exchange_n(ll, (bool)true, __ATOMIC_SEQ_CST); |
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172 | } |
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173 | |
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174 | // Release |
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175 | static inline void __atomic_unlock(volatile bool * ll) { |
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176 | /* paranoid */ verify(*ll); |
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177 | __atomic_store_n(ll, (bool)false, __ATOMIC_RELEASE); |
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178 | } |
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179 | |
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180 | //----------------------------------------------------------------------- |
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181 | // Reader-Writer lock protecting the ready-queues |
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182 | // while this lock is mostly generic some aspects |
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183 | // have been hard-coded to for the ready-queue for |
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184 | // simplicity and performance |
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185 | struct __scheduler_RWLock_t { |
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186 | // total cachelines allocated |
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187 | unsigned int max; |
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188 | |
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189 | // cachelines currently in use |
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190 | volatile unsigned int alloc; |
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191 | |
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192 | // cachelines ready to itereate over |
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193 | // (!= to alloc when thread is in second half of doregister) |
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194 | volatile unsigned int ready; |
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195 | |
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196 | // writer lock |
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197 | volatile bool write_lock; |
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198 | |
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199 | // data pointer |
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200 | volatile bool * volatile * data; |
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201 | }; |
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202 | |
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203 | void ?{}(__scheduler_RWLock_t & this); |
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204 | void ^?{}(__scheduler_RWLock_t & this); |
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205 | |
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206 | extern __scheduler_RWLock_t * __scheduler_lock; |
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207 | |
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208 | //----------------------------------------------------------------------- |
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209 | // Reader side : acquire when using the ready queue to schedule but not |
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210 | // creating/destroying queues |
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211 | static inline void ready_schedule_lock(void) with(*__scheduler_lock) { |
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212 | /* paranoid */ verify( ! __preemption_enabled() ); |
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213 | /* paranoid */ verify( ! kernelTLS().in_sched_lock ); |
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214 | /* paranoid */ verify( data[kernelTLS().sched_id] == &kernelTLS().sched_lock ); |
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215 | /* paranoid */ verify( !kernelTLS().this_processor || kernelTLS().this_processor->unique_id == kernelTLS().sched_id ); |
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216 | |
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217 | // Step 1 : make sure no writer are in the middle of the critical section |
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218 | while(__atomic_load_n(&write_lock, (int)__ATOMIC_RELAXED)) |
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219 | Pause(); |
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220 | |
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221 | // Fence needed because we don't want to start trying to acquire the lock |
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222 | // before we read a false. |
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223 | // Not needed on x86 |
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224 | // std::atomic_thread_fence(std::memory_order_seq_cst); |
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225 | |
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226 | // Step 2 : acquire our local lock |
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227 | __atomic_acquire( &kernelTLS().sched_lock ); |
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228 | /*paranoid*/ verify(kernelTLS().sched_lock); |
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229 | |
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230 | #ifdef __CFA_WITH_VERIFY__ |
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231 | // Debug, check if this is owned for reading |
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232 | kernelTLS().in_sched_lock = true; |
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233 | #endif |
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234 | } |
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235 | |
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236 | static inline void ready_schedule_unlock(void) with(*__scheduler_lock) { |
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237 | /* paranoid */ verify( ! __preemption_enabled() ); |
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238 | /* paranoid */ verify( data[kernelTLS().sched_id] == &kernelTLS().sched_lock ); |
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239 | /* paranoid */ verify( !kernelTLS().this_processor || kernelTLS().this_processor->unique_id == kernelTLS().sched_id ); |
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240 | /* paranoid */ verify( kernelTLS().sched_lock ); |
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241 | /* paranoid */ verify( kernelTLS().in_sched_lock ); |
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242 | #ifdef __CFA_WITH_VERIFY__ |
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243 | // Debug, check if this is owned for reading |
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244 | kernelTLS().in_sched_lock = false; |
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245 | #endif |
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246 | __atomic_unlock(&kernelTLS().sched_lock); |
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247 | } |
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248 | |
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249 | #ifdef __CFA_WITH_VERIFY__ |
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250 | static inline bool ready_schedule_islocked(void) { |
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251 | /* paranoid */ verify( ! __preemption_enabled() ); |
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252 | /* paranoid */ verify( (!kernelTLS().in_sched_lock) || kernelTLS().sched_lock ); |
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253 | return kernelTLS().sched_lock; |
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254 | } |
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255 | |
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256 | static inline bool ready_mutate_islocked() { |
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257 | return __scheduler_lock->write_lock; |
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258 | } |
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259 | #endif |
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260 | |
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261 | //----------------------------------------------------------------------- |
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262 | // Writer side : acquire when changing the ready queue, e.g. adding more |
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263 | // queues or removing them. |
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264 | uint_fast32_t ready_mutate_lock( void ); |
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265 | |
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266 | void ready_mutate_unlock( uint_fast32_t /* value returned by lock */ ); |
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267 | |
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268 | //----------------------------------------------------------------------- |
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269 | // Lock-Free registering/unregistering of threads |
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270 | // Register a processor to a given cluster and get its unique id in return |
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271 | // For convenience, also acquires the lock |
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272 | static inline [unsigned, uint_fast32_t] ready_mutate_register() { |
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273 | unsigned id = register_proc_id(); |
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274 | uint_fast32_t last = ready_mutate_lock(); |
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275 | return [id, last]; |
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276 | } |
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277 | |
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278 | // Unregister a processor from a given cluster using its id, getting back the original pointer |
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279 | // assumes the lock is acquired |
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280 | static inline void ready_mutate_unregister( unsigned id, uint_fast32_t last_s ) { |
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281 | ready_mutate_unlock( last_s ); |
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282 | unregister_proc_id( id ); |
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283 | } |
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284 | |
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285 | //----------------------------------------------------------------------- |
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286 | // Cluster idle lock/unlock |
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287 | static inline void lock(__cluster_proc_list & this) { |
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288 | /* paranoid */ verify( ! __preemption_enabled() ); |
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289 | |
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290 | // Start by locking the global RWlock so that we know no-one is |
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291 | // adding/removing processors while we mess with the idle lock |
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292 | ready_schedule_lock(); |
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293 | |
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294 | lock( this.lock __cfaabi_dbg_ctx2 ); |
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295 | |
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296 | /* paranoid */ verify( ! __preemption_enabled() ); |
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297 | } |
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298 | |
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299 | static inline bool try_lock(__cluster_proc_list & this) { |
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300 | /* paranoid */ verify( ! __preemption_enabled() ); |
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301 | |
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302 | // Start by locking the global RWlock so that we know no-one is |
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303 | // adding/removing processors while we mess with the idle lock |
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304 | ready_schedule_lock(); |
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305 | |
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306 | if(try_lock( this.lock __cfaabi_dbg_ctx2 )) { |
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307 | // success |
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308 | /* paranoid */ verify( ! __preemption_enabled() ); |
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309 | return true; |
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310 | } |
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311 | |
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312 | // failed to lock |
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313 | ready_schedule_unlock(); |
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314 | |
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315 | /* paranoid */ verify( ! __preemption_enabled() ); |
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316 | return false; |
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317 | } |
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318 | |
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319 | static inline void unlock(__cluster_proc_list & this) { |
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320 | /* paranoid */ verify( ! __preemption_enabled() ); |
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321 | |
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322 | unlock(this.lock); |
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323 | |
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324 | // Release the global lock, which we acquired when locking |
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325 | ready_schedule_unlock(); |
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326 | |
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327 | /* paranoid */ verify( ! __preemption_enabled() ); |
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328 | } |
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329 | |
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330 | //======================================================================= |
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331 | // Ready-Queue API |
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332 | //----------------------------------------------------------------------- |
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333 | // push thread onto a ready queue for a cluster |
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334 | // returns true if the list was previously empty, false otherwise |
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335 | __attribute__((hot)) void push(struct cluster * cltr, struct thread$ * thrd, unpark_hint hint); |
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336 | |
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337 | //----------------------------------------------------------------------- |
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338 | // pop thread from the local queues of a cluster |
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339 | // returns 0p if empty |
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340 | // May return 0p spuriously |
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341 | __attribute__((hot)) struct thread$ * pop_fast(struct cluster * cltr); |
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342 | |
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343 | //----------------------------------------------------------------------- |
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344 | // pop thread from any ready queue of a cluster |
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345 | // returns 0p if empty |
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346 | // May return 0p spuriously |
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347 | __attribute__((hot)) struct thread$ * pop_slow(struct cluster * cltr); |
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348 | |
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349 | //----------------------------------------------------------------------- |
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350 | // search all ready queues of a cluster for any thread |
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351 | // returns 0p if empty |
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352 | // guaranteed to find any threads added before this call |
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353 | __attribute__((hot)) struct thread$ * pop_search(struct cluster * cltr); |
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354 | |
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355 | //----------------------------------------------------------------------- |
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356 | // get preferred ready for new thread |
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357 | unsigned ready_queue_new_preferred(); |
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358 | |
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359 | //----------------------------------------------------------------------- |
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360 | // Increase the width of the ready queue (number of lanes) by 4 |
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361 | void ready_queue_grow (struct cluster * cltr); |
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362 | |
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363 | //----------------------------------------------------------------------- |
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364 | // Decrease the width of the ready queue (number of lanes) by 4 |
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365 | void ready_queue_shrink(struct cluster * cltr); |
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366 | |
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367 | |
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368 | // Local Variables: // |
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369 | // mode: c // |
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370 | // tab-width: 4 // |
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371 | // End: // |
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