annotate vmalloc.c @ 70:f9b60012fd74

working ucontext version
author Merten Sach <msach@mailbox.tu-berlin.de>
date Fri, 27 May 2011 12:35:40 +0200
parents 13b22ffb8a2f
children 9ddbb071142d
rev   line source
Me@50 1 /*
Me@50 2 * Copyright 2009 OpenSourceCodeStewardshipFoundation.org
Me@50 3 * Licensed under GNU General Public License version 2
Me@50 4 *
Me@50 5 * Author: seanhalle@yahoo.com
Me@50 6 *
Me@50 7 * Created on November 14, 2009, 9:07 PM
Me@50 8 */
Me@50 9
Me@50 10 #include <malloc.h>
Me@53 11 #include <stdlib.h>
Me@50 12
Me@50 13 #include "VMS.h"
Me@68 14 #include "Histogram/Histogram.h"
Me@50 15
Me@50 16 /*Helper function
Me@50 17 *Insert a newly generated free chunk into the first spot on the free list.
Me@50 18 * The chunk is cast as a MallocProlog, so the various pointers in it are
Me@50 19 * accessed with C's help -- and the size of the prolog is easily added to
Me@50 20 * the pointer when a chunk is returned to the app -- so C handles changes
Me@50 21 * in pointer sizes among machines.
Me@50 22 *
Me@50 23 *The list head is a normal MallocProlog struct -- identified by its
Me@50 24 * prevChunkInFreeList being NULL -- the only one.
Me@50 25 *
Me@50 26 *The end of the list is identified by next chunk being NULL, as usual.
Me@50 27 */
Me@50 28 void inline
Me@50 29 add_chunk_to_free_list( MallocProlog *chunk, MallocProlog *listHead )
Me@50 30 {
Me@50 31 chunk->nextChunkInFreeList = listHead->nextChunkInFreeList;
Me@50 32 if( chunk->nextChunkInFreeList != NULL ) //if not last in free list
Me@50 33 chunk->nextChunkInFreeList->prevChunkInFreeList = chunk;
Me@50 34 chunk->prevChunkInFreeList = listHead;
Me@50 35 listHead->nextChunkInFreeList = chunk;
Me@50 36 }
Me@50 37
Me@50 38
Me@50 39 /*This is sequential code, meant to only be called from the Master, not from
Me@50 40 * any slave VPs.
Me@50 41 *Search down list, checking size by the nextHigherInMem pointer, to find
Me@50 42 * first chunk bigger than size needed.
Me@50 43 *Shave off the extra and make it into a new free-list element, hook it in
Me@50 44 * then return the address of the found element plus size of prolog.
Me@50 45 *
Me@50 46 *Will find a
Me@50 47 */
Me@50 48 void *
Me@50 49 VMS__malloc( int32 sizeRequested )
Me@50 50 { MallocProlog *foundElem = NULL, *currElem, *newElem;
Me@50 51 int32 amountExtra, foundElemIsTopOfHeap, sizeConsumed,sizeOfFound;
Me@50 52
Me@65 53 //============================= MEASUREMENT STUFF ========================
Me@65 54 #ifdef MEAS__TIME_MALLOC
Me@65 55 int32 startStamp, endStamp;
Me@65 56 saveLowTimeStampCountInto( startStamp );
Me@65 57 #endif
Me@65 58 //========================================================================
Me@65 59
Me@50 60 //step up the size to be aligned at 16-byte boundary, prob better ways
Me@50 61 sizeRequested = ((sizeRequested + 16) >> 4) << 4;
Me@50 62 currElem = (_VMSMasterEnv->freeListHead)->nextChunkInFreeList;
Me@50 63
Me@50 64 while( currElem != NULL )
Me@50 65 { //check if size of currElem is big enough
Me@50 66 sizeOfFound=(int32)((char*)currElem->nextHigherInMem -(char*)currElem);
Me@50 67 amountExtra = sizeOfFound - sizeRequested - sizeof(MallocProlog);
Me@50 68 if( amountExtra > 0 )
Me@50 69 { //found it, get out of loop
Me@50 70 foundElem = currElem;
Me@50 71 currElem = NULL;
Me@50 72 }
Me@50 73 else
Me@50 74 currElem = currElem->nextChunkInFreeList;
Me@50 75 }
Me@50 76
Me@50 77 if( foundElem == NULL )
Me@55 78 { ERROR("\nmalloc failed\n")
Me@60 79 return (void *)NULL; //indicates malloc failed
Me@50 80 }
Me@50 81 //Using a kludge to identify the element that is the top chunk in the
Me@50 82 // heap -- saving top-of-heap addr in head's nextHigherInMem -- and
Me@50 83 // save addr of start of heap in head's nextLowerInMem
Me@50 84 //Will handle top of Heap specially
Me@50 85 foundElemIsTopOfHeap = foundElem->nextHigherInMem ==
Me@50 86 _VMSMasterEnv->freeListHead->nextHigherInMem;
Me@50 87
Me@50 88 //before shave off and try to insert new elem, remove found elem
Me@50 89 //note, foundElem will never be the head, so always has valid prevChunk
Me@50 90 foundElem->prevChunkInFreeList->nextChunkInFreeList =
Me@50 91 foundElem->nextChunkInFreeList;
Me@50 92 if( foundElem->nextChunkInFreeList != NULL )
Me@50 93 { foundElem->nextChunkInFreeList->prevChunkInFreeList =
Me@50 94 foundElem->prevChunkInFreeList;
Me@50 95 }
Me@50 96 foundElem->prevChunkInFreeList = NULL;//indicates elem currently allocated
Me@50 97
Me@50 98 //if enough, turn extra into new elem & insert it
Me@50 99 if( amountExtra > 64 )
Me@50 100 { //make new elem by adding to addr of curr elem then casting
Me@50 101 sizeConsumed = sizeof(MallocProlog) + sizeRequested;
Me@50 102 newElem = (MallocProlog *)( (char *)foundElem + sizeConsumed );
Me@50 103 newElem->nextHigherInMem = foundElem->nextHigherInMem;
Me@50 104 newElem->nextLowerInMem = foundElem;
Me@50 105 foundElem->nextHigherInMem = newElem;
Me@50 106
Me@50 107 if( ! foundElemIsTopOfHeap )
Me@50 108 { //there is no next higher for top of heap, so can't write to it
Me@50 109 newElem->nextHigherInMem->nextLowerInMem = newElem;
Me@50 110 }
Me@50 111 add_chunk_to_free_list( newElem, _VMSMasterEnv->freeListHead );
Me@50 112 }
Me@50 113 else
Me@50 114 {
Me@50 115 sizeConsumed = sizeOfFound;
Me@50 116 }
Me@50 117 _VMSMasterEnv->amtOfOutstandingMem += sizeConsumed;
Me@50 118
Me@65 119 //============================= MEASUREMENT STUFF ========================
Me@65 120 #ifdef MEAS__TIME_MALLOC
Me@65 121 saveLowTimeStampCountInto( endStamp );
Me@65 122 addIntervalToHist( startStamp, endStamp, _VMSMasterEnv->mallocTimeHist );
Me@65 123 #endif
Me@65 124 //========================================================================
Me@65 125
Me@50 126 //skip over the prolog by adding its size to the pointer return
Me@50 127 return (void *)((char *)foundElem + sizeof(MallocProlog));
Me@50 128 }
Me@50 129
Me@50 130
Me@50 131 /*This is sequential code -- only to be called from the Master
Me@50 132 * When free, subtract the size of prolog from pointer, then cast it to a
Me@50 133 * MallocProlog. Then check the nextLower and nextHigher chunks to see if
Me@50 134 * one or both are also free, and coalesce if so, and if neither free, then
Me@50 135 * add this one to free-list.
Me@50 136 */
Me@50 137 void
Me@50 138 VMS__free( void *ptrToFree )
Me@50 139 { MallocProlog *elemToFree, *nextLowerElem, *nextHigherElem;
Me@50 140 int32 lowerExistsAndIsFree, higherExistsAndIsFree, sizeOfElem;
Me@50 141
Me@65 142 //============================= MEASUREMENT STUFF ========================
Me@65 143 #ifdef MEAS__TIME_MALLOC
Me@65 144 int32 startStamp, endStamp;
Me@65 145 saveLowTimeStampCountInto( startStamp );
Me@65 146 #endif
Me@65 147 //========================================================================
Me@65 148
Me@53 149 if( ptrToFree < (void*)_VMSMasterEnv->freeListHead->nextLowerInMem ||
Me@53 150 ptrToFree > (void*)_VMSMasterEnv->freeListHead->nextHigherInMem )
Me@50 151 { //outside the range of data owned by VMS's malloc, so do nothing
Me@50 152 return;
Me@50 153 }
Me@50 154 //subtract size of prolog to get pointer to prolog, then cast
Me@50 155 elemToFree = (MallocProlog *)((char *)ptrToFree - sizeof(MallocProlog));
Me@50 156 sizeOfElem =(int32)((char*)elemToFree->nextHigherInMem-(char*)elemToFree);
Me@53 157
Me@53 158 if( elemToFree->prevChunkInFreeList != NULL )
Me@53 159 { printf( "error: freeing same element twice!" ); exit(1);
Me@53 160 }
Me@53 161
Me@50 162 _VMSMasterEnv->amtOfOutstandingMem -= sizeOfElem;
Me@50 163
Me@50 164 nextLowerElem = elemToFree->nextLowerInMem;
Me@50 165 nextHigherElem = elemToFree->nextHigherInMem;
Me@50 166
Me@50 167 if( nextHigherElem == NULL )
Me@50 168 higherExistsAndIsFree = FALSE;
Me@50 169 else //okay exists, now check if in the free-list by checking back ptr
Me@50 170 higherExistsAndIsFree = (nextHigherElem->prevChunkInFreeList != NULL);
Me@50 171
Me@50 172 if( nextLowerElem == NULL )
Me@50 173 lowerExistsAndIsFree = FALSE;
Me@50 174 else //okay, it exists, now check if it's free
Me@50 175 lowerExistsAndIsFree = (nextLowerElem->prevChunkInFreeList != NULL);
Me@50 176
Me@50 177
Me@50 178 //now, know what exists and what's free
Me@50 179 if( lowerExistsAndIsFree )
Me@50 180 { if( higherExistsAndIsFree )
Me@50 181 { //both exist and are free, so coalesce all three
Me@50 182 //First, remove higher from free-list
Me@50 183 nextHigherElem->prevChunkInFreeList->nextChunkInFreeList =
Me@50 184 nextHigherElem->nextChunkInFreeList;
Me@50 185 if( nextHigherElem->nextChunkInFreeList != NULL ) //end-of-list?
Me@50 186 nextHigherElem->nextChunkInFreeList->prevChunkInFreeList =
Me@50 187 nextHigherElem->prevChunkInFreeList;
Me@50 188 //Now, fix-up sequence-in-mem list -- by side-effect, this also
Me@50 189 // changes size of the lower elem, which is still in free-list
Me@50 190 nextLowerElem->nextHigherInMem = nextHigherElem->nextHigherInMem;
Me@50 191 if( nextHigherElem->nextHigherInMem !=
Me@50 192 _VMSMasterEnv->freeListHead->nextHigherInMem )
Me@50 193 nextHigherElem->nextHigherInMem->nextLowerInMem = nextLowerElem;
Me@50 194 //notice didn't do anything to elemToFree -- it simply is no
Me@50 195 // longer reachable from any of the lists. Wonder if could be a
Me@50 196 // security leak because left valid addresses in it,
Me@50 197 // but don't care for now.
Me@50 198 }
Me@50 199 else
Me@50 200 { //lower is the only of the two that exists and is free,
Me@50 201 //In this case, no adjustment to free-list, just change mem-list.
Me@50 202 // By side-effect, changes size of the lower elem
Me@50 203 nextLowerElem->nextHigherInMem = elemToFree->nextHigherInMem;
Me@50 204 if( elemToFree->nextHigherInMem !=
Me@50 205 _VMSMasterEnv->freeListHead->nextHigherInMem )
Me@50 206 elemToFree->nextHigherInMem->nextLowerInMem = nextLowerElem;
Me@50 207 }
Me@50 208 }
Me@50 209 else
Me@50 210 { //lower either doesn't exist or isn't free, so check higher
Me@50 211 if( higherExistsAndIsFree )
Me@50 212 { //higher exists and is the only of the two free
Me@50 213 //First, in free-list, replace higher elem with the one to free
Me@50 214 elemToFree->nextChunkInFreeList=nextHigherElem->nextChunkInFreeList;
Me@50 215 elemToFree->prevChunkInFreeList=nextHigherElem->prevChunkInFreeList;
Me@50 216 elemToFree->prevChunkInFreeList->nextChunkInFreeList = elemToFree;
Me@50 217 if( elemToFree->nextChunkInFreeList != NULL ) // end-of-list?
Me@50 218 elemToFree->nextChunkInFreeList->prevChunkInFreeList =elemToFree;
Me@50 219 //Now chg mem-list. By side-effect, changes size of elemToFree
Me@50 220 elemToFree->nextHigherInMem = nextHigherElem->nextHigherInMem;
Me@50 221 if( elemToFree->nextHigherInMem !=
Me@50 222 _VMSMasterEnv->freeListHead->nextHigherInMem )
Me@50 223 elemToFree->nextHigherInMem->nextLowerInMem = elemToFree;
Me@50 224 }
Me@50 225 else
Me@50 226 { //neither lower nor higher is availabe to coalesce so add to list
Me@50 227 // this makes prev chunk ptr non-null, which indicates it's free
Me@50 228 elemToFree->nextChunkInFreeList =
Me@50 229 _VMSMasterEnv->freeListHead->nextChunkInFreeList;
Me@50 230 _VMSMasterEnv->freeListHead->nextChunkInFreeList = elemToFree;
Me@50 231 if( elemToFree->nextChunkInFreeList != NULL ) // end-of-list?
Me@50 232 elemToFree->nextChunkInFreeList->prevChunkInFreeList =elemToFree;
Me@50 233 elemToFree->prevChunkInFreeList = _VMSMasterEnv->freeListHead;
Me@50 234 }
Me@50 235 }
Me@65 236 //============================= MEASUREMENT STUFF ========================
Me@65 237 #ifdef MEAS__TIME_MALLOC
Me@65 238 saveLowTimeStampCountInto( endStamp );
Me@65 239 addIntervalToHist( startStamp, endStamp, _VMSMasterEnv->freeTimeHist );
Me@65 240 #endif
Me@65 241 //========================================================================
Me@50 242
Me@50 243 }
Me@50 244
Me@50 245
Me@53 246 /*Allocates memory from the external system -- higher overhead
Me@53 247 *
Me@53 248 *Because of Linux's malloc throwing bizarre random faults when malloc is
Me@53 249 * used inside a VMS virtual processor, have to pass this as a request and
Me@53 250 * have the core loop do it when it gets around to it -- will look for these
Me@53 251 * chores leftover from the previous animation of masterVP the next time it
Me@53 252 * goes to animate the masterVP -- so it takes two separate masterVP
Me@53 253 * animations, separated by work, to complete an external malloc or
Me@53 254 * external free request.
Me@53 255 *
Me@53 256 *Thinking core loop accepts signals -- just looks if signal-location is
Me@53 257 * empty or not --
Me@53 258 */
Me@53 259 void *
Me@53 260 VMS__malloc_in_ext( int32 sizeRequested )
Me@53 261 {
Me@53 262 /*
Me@53 263 //This is running in the master, so no chance for multiple cores to be
Me@53 264 // competing for the core's flag.
Me@53 265 if( *(_VMSMasterEnv->coreLoopSignalAddr[ 0 ]) != 0 )
Me@53 266 { //something has already signalled to core loop, so save the signal
Me@53 267 // and look, next time master animated, to see if can send it.
Me@53 268 //Note, the addr to put a signal is in the coreloop's frame, so just
Me@53 269 // checks it each time through -- make it volatile to avoid GCC
Me@53 270 // optimizations -- it's a coreloop local var that only changes
Me@53 271 // after jumping away. The signal includes the addr to send the
Me@53 272 //return to -- even if just empty return completion-signal
Me@53 273 //
Me@53 274 //save the signal in some queue that the master looks at each time
Me@53 275 // it starts up -- one loc says if empty for fast common case --
Me@53 276 //something like that -- want to hide this inside this call -- but
Me@53 277 // think this has to come as a request -- req handler gives procr
Me@53 278 // back to master loop, which gives it back to req handler at point
Me@53 279 // it sees that core loop has sent return signal. Something like
Me@53 280 // that.
Me@53 281 saveTheSignal
Me@53 282
Me@53 283 }
Me@53 284 coreSigData->type = malloc;
Me@53 285 coreSigData->sizeToMalloc = sizeRequested;
Me@53 286 coreSigData->locToSignalCompletion = &figureOut;
Me@53 287 _VMSMasterEnv->coreLoopSignals[ 0 ] = coreSigData;
Me@53 288 */
Me@53 289 //just risk system-stack faults until get this figured out
Me@53 290 return malloc( sizeRequested );
Me@53 291 }
Me@53 292
Me@53 293
Me@53 294 /*Frees memory that was allocated in the external system -- higher overhead
Me@53 295 *
Me@53 296 *As noted in external malloc comment, this is clunky 'cause the free has
Me@53 297 * to be called in the core loop.
Me@53 298 */
Me@53 299 void
Me@53 300 VMS__free_in_ext( void *ptrToFree )
Me@53 301 {
Me@53 302 //just risk system-stack faults until get this figured out
Me@53 303 free( ptrToFree );
Me@53 304
Me@53 305 //TODO: fix this -- so
Me@53 306 }
Me@53 307
Me@53 308
Me@50 309 /*Designed to be called from the main thread outside of VMS, during init
Me@50 310 */
Me@50 311 MallocProlog *
Me@53 312 VMS_ext__create_free_list()
Me@50 313 { MallocProlog *freeListHead, *firstChunk;
Me@50 314
Me@50 315 //Note, this is running in the main thread -- all increases in malloc
Me@50 316 // mem and all frees of it must be done in this thread, with the
Me@50 317 // thread's original stack available
Me@50 318 freeListHead = malloc( sizeof(MallocProlog) );
Me@50 319 firstChunk = malloc( MALLOC_ADDITIONAL_MEM_FROM_OS_SIZE );
Me@50 320 if( firstChunk == NULL ) {printf("malloc error\n"); exit(1);}
Me@50 321
Me@50 322 freeListHead->prevChunkInFreeList = NULL;
Me@50 323 //Use this addr to free the heap when cleanup
Me@50 324 freeListHead->nextLowerInMem = firstChunk;
Me@50 325 //to identify top-of-heap elem, compare this addr to elem's next higher
Me@53 326 freeListHead->nextHigherInMem = (void*)( (char*)firstChunk +
Me@53 327 MALLOC_ADDITIONAL_MEM_FROM_OS_SIZE);
Me@50 328 freeListHead->nextChunkInFreeList = firstChunk;
Me@50 329
Me@50 330 firstChunk->nextChunkInFreeList = NULL;
Me@50 331 firstChunk->prevChunkInFreeList = freeListHead;
Me@50 332 //next Higher has to be set to top of chunk, so can calc size in malloc
Me@53 333 firstChunk->nextHigherInMem = (void*)( (char*)firstChunk +
Me@53 334 MALLOC_ADDITIONAL_MEM_FROM_OS_SIZE);
Me@50 335 firstChunk->nextLowerInMem = NULL; //identifies as bott of heap
Me@53 336
Me@53 337 _VMSMasterEnv->amtOfOutstandingMem = 0; //none allocated yet
Me@50 338
Me@50 339 return freeListHead;
Me@50 340 }
Me@50 341
Me@50 342
Me@50 343 /*Designed to be called from the main thread outside of VMS, during cleanup
Me@50 344 */
Me@50 345 void
Me@50 346 VMS_ext__free_free_list( MallocProlog *freeListHead )
Me@50 347 {
Me@50 348 //stashed a ptr to the one and only bug chunk malloc'd from OS in the
Me@50 349 // free list head's next lower in mem pointer
Me@50 350 free( freeListHead->nextLowerInMem );
Me@50 351
Me@50 352 //don't free the head -- it'll be in an array eventually -- free whole
Me@50 353 // array when all the free lists linked from it have already been freed
Me@50 354 }
Me@50 355