mirror of
https://github.com/reactos/reactos.git
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446 lines
8.7 KiB
C
446 lines
8.7 KiB
C
/* $Id: fiber.c,v 1.1 2004/10/21 05:12:02 sedwards Exp $
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*/
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#include <assert.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <tchar.h>
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#include <windows.h>
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#ifndef InitializeListHead
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#define InitializeListHead(PLH__) ((PLH__)->Flink = (PLH__)->Blink = (PLH__))
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#endif
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#ifndef IsListEmpty
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#define IsListEmpty(PLH__) ((PLH__)->Flink == (PVOID)(PLH__))
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#endif
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#ifndef RemoveEntryList
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#define RemoveEntryList(PLE__) \
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{ \
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PLIST_ENTRY pleBack__ = (PLIST_ENTRY)((PLE__)->Blink); \
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PLIST_ENTRY pleForward__ = (PLIST_ENTRY)((PLE__)->Flink); \
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\
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pleBack__->Flink = pleForward__; \
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pleForward__->Blink = pleBack__; \
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}
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#endif
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#ifndef InsertTailList
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#define InsertTailList(PLH__, PLE__) \
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{ \
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PLIST_ENTRY pleListHead__ = (PLH__); \
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PLIST_ENTRY pleBlink__ = (PLIST_ENTRY)((PLH__)->Blink); \
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\
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(PLE__)->Flink = pleListHead__; \
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(PLE__)->Blink = pleBlink__; \
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pleBlink__->Flink = (PLE__); \
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pleListHead__->Blink = (PLE__); \
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}
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#endif
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#ifndef RemoveHeadList
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#define RemoveHeadList(PLH__) \
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(PLIST_ENTRY)((PLH__)->Flink); \
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RemoveEntryList((PLIST_ENTRY)((PLH__)->Flink));
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#endif
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#define FIBERTEST_COUNT 500
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struct FiberData
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{
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unsigned nMagic;
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unsigned nId;
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unsigned nPrio;
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unsigned nRealPrio;
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PVOID pFiber;
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LIST_ENTRY leQueue;
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int nQuantumQueued;
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int nBoost;
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struct FiberData * pfdPrev;
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int bExitPrev;
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};
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static LIST_ENTRY a_leQueues[32];
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static unsigned nQuantum = 0;
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static struct FiberData * pfdLastStarveScan = NULL;
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void Fbt_Create(int);
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void Fbt_Exit(void);
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void Fbt_Yield(void);
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struct FiberData * Fbt_GetCurrent(void);
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unsigned Fbt_GetCurrentId(void);
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VOID CALLBACK Fbt_Startup(PVOID);
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void Fbt_Dispatch(struct FiberData *, int);
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void Fbt_AfterSwitch(struct FiberData *);
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void DoStuff(void);
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struct FiberData * Fbt_GetCurrent(VOID)
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{
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return GetFiberData();
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}
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unsigned Fbt_GetCurrentId(VOID)
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{
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return Fbt_GetCurrent()->nId;
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}
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void Fbt_Yield(VOID)
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{
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struct FiberData * pfdCur;
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pfdCur = Fbt_GetCurrent();
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if(pfdCur->nBoost)
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{
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-- pfdCur->nBoost;
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if(!pfdCur->nBoost)
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pfdCur->nPrio = pfdCur->nRealPrio;
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}
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else if((rand() % 100) > 50 - (45 * pfdCur->nPrio) / 32)
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Fbt_Dispatch(pfdCur, 0);
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}
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void Fbt_AfterSwitch(struct FiberData * pfdCur)
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{
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struct FiberData * pfdPrev;
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pfdPrev = pfdCur->pfdPrev;
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/* The previous fiber left some homework for us */
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if(pfdPrev)
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{
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/* Kill the predecessor */
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if(pfdCur->bExitPrev)
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{
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if(pfdLastStarveScan == pfdPrev)
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pfdLastStarveScan = 0;
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DeleteFiber(pfdPrev->pFiber);
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free(pfdPrev);
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}
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/* Enqueue the previous fiber in the correct ready queue */
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else
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{
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/* Remember the quantum in which the previous fiber was queued */
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pfdPrev->nQuantumQueued = nQuantum;
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/* Disable the anti-starvation boost */
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if(pfdPrev->nBoost)
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{
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pfdPrev->nBoost = 0;
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pfdPrev->nPrio = pfdPrev->nRealPrio;
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}
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/* Enqueue the previous fiber */
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InsertTailList
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(
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&a_leQueues[pfdPrev->nPrio],
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&pfdPrev->leQueue
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);
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}
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}
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}
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VOID CALLBACK Fbt_Startup(PVOID pParam)
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{
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assert(pParam == GetFiberData());
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Fbt_AfterSwitch(pParam);
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DoStuff();
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Fbt_Exit();
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}
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void Fbt_Dispatch(struct FiberData * pfdCur, int bExit)
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{
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UCHAR i;
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UCHAR n;
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struct FiberData * pfdNext;
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assert(pfdCur == GetFiberData());
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++ nQuantum;
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/* Every ten quantums check for starving threads */
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/* FIXME: this implementation of starvation prevention isn't that great */
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if(nQuantum % 10 == 0)
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{
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int j;
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int k;
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int b;
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int bResume;
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PLIST_ENTRY ple = NULL;
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bResume = 0;
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i = 0;
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/* Pick up from where we left last time */
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if(pfdLastStarveScan)
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{
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unsigned nPrio;
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nPrio = pfdLastStarveScan->nPrio;
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/* The last fiber we scanned for starvation isn't queued anymore */
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if(IsListEmpty(&pfdLastStarveScan->leQueue))
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/* Scan the ready queue for its priority */
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i = nPrio;
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/* Last fiber for its priority level */
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else if(pfdLastStarveScan->leQueue.Flink == &a_leQueues[nPrio])
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/* Scan the ready queue for the next priority level */
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i = nPrio + 1;
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/* Scan the next fiber in the ready queue */
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else
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{
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i = nPrio;
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ple = pfdLastStarveScan->leQueue.Flink;
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bResume = 1;
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}
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/* Priority levels 15-31 are never checked for starvation */
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if(i >= 15)
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{
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if(bResume)
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bResume = 0;
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i = 0;
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}
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}
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/*
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Scan at most 16 threads, in the priority range 0-14, applying in total at
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most 10 boosts. This loop scales O(1)
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*/
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for(j = 0, k = 0, b = 0; j < 16 && k < 15 && b < 10; ++ j)
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{
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unsigned nDiff;
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/* No previous state to resume from */
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if(!bResume)
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{
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int nQueue;
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/* Get the first element in the current queue */
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nQueue = (k + i) % 15;
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if(IsListEmpty(&a_leQueues[nQueue]))
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{
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++ k;
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continue;
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}
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ple = (PLIST_ENTRY)a_leQueues[nQueue].Flink;
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}
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else
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bResume = 0;
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/* Get the current fiber */
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pfdLastStarveScan = CONTAINING_RECORD(ple, struct FiberData, leQueue);
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assert(pfdLastStarveScan->nMagic == 0x12345678);
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assert(pfdLastStarveScan != pfdCur);
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/* Calculate the number of quantums the fiber has been in the queue */
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if(nQuantum > pfdLastStarveScan->nQuantumQueued)
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nDiff = nQuantum - pfdLastStarveScan->nQuantumQueued;
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else
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nDiff = UINT_MAX - pfdLastStarveScan->nQuantumQueued + nQuantum;
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/* The fiber has been ready for more than 30 quantums: it's starving */
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if(nDiff > 30)
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{
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/* Plus one boost applied */
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++ b;
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/* Apply the boost */
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pfdLastStarveScan->nBoost = 1;
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pfdLastStarveScan->nRealPrio = pfdLastStarveScan->nPrio;
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pfdLastStarveScan->nPrio = 15;
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/* Re-enqueue the fiber in the correct priority queue */
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RemoveEntryList(&pfdLastStarveScan->leQueue);
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InsertTailList(&a_leQueues[15], &pfdLastStarveScan->leQueue);
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}
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}
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}
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pfdNext = NULL;
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/* This fiber is going to die: scan all ready queues */
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if(bExit)
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n = 1;
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/*
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Scan only ready queues for priorities greater than or equal to the priority of
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the current thread (round-robin)
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*/
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else
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n = pfdCur->nPrio + 1;
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/* This loop scales O(1) */
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for(i = 32; i >= n; -- i)
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{
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PLIST_ENTRY pleNext;
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/* No fiber ready for this priority level */
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if(IsListEmpty(&a_leQueues[i - 1]))
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continue;
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/* Get the next ready fiber */
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pleNext = RemoveHeadList(&a_leQueues[i - 1]);
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InitializeListHead(pleNext);
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pfdNext = CONTAINING_RECORD(pleNext, struct FiberData, leQueue);
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assert(pfdNext->pFiber != GetCurrentFiber());
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assert(pfdNext->nMagic == 0x12345678);
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break;
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}
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/* Next fiber chosen */
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if(pfdNext)
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{
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/* Give some homework to the next fiber */
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pfdNext->pfdPrev = pfdCur;
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pfdNext->bExitPrev = bExit;
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/* Switch to the next fiber */
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SwitchToFiber(pfdNext->pFiber);
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/* Complete the switch back to this fiber */
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Fbt_AfterSwitch(pfdCur);
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}
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/* No next fiber, and current fiber exiting */
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else if(bExit)
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{
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PVOID pCurFiber;
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/* Delete the current fiber. This kills the thread and stops the simulation */
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if(pfdLastStarveScan == pfdCur)
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pfdLastStarveScan = NULL;
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pCurFiber = pfdCur->pFiber;
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free(pfdCur);
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DeleteFiber(pCurFiber);
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}
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/* No next fiber: continue running the current one */
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}
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void Fbt_Exit(VOID)
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{
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Fbt_Dispatch(GetFiberData(), 1);
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}
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void Fbt_CreateFiber(int bInitial)
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{
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PVOID pFiber;
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struct FiberData * pData;
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static int s_bFiberPrioSeeded = 0;
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static LONG s_nFiberIdSeed = 0;
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pData = malloc(sizeof(struct FiberData));
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assert(pData);
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if(bInitial)
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pFiber = ConvertThreadToFiber(pData);
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else
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pFiber = CreateFiber(0, Fbt_Startup, pData);
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if(!s_bFiberPrioSeeded)
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{
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unsigned nFiberPrioSeed;
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time_t tCurTime;
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tCurTime = time(NULL);
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memcpy(&nFiberPrioSeed, &tCurTime, sizeof(nFiberPrioSeed));
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srand(nFiberPrioSeed);
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s_bFiberPrioSeeded = 1;
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}
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assert(pFiber);
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pData->nMagic = 0x12345678;
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pData->nId = InterlockedIncrement(&s_nFiberIdSeed);
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pData->nPrio = rand() % 32;
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pData->pFiber = pFiber;
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pData->nQuantumQueued = 0;
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pData->nBoost = 0;
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pData->nRealPrio = pData->nPrio;
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pData->pfdPrev = NULL;
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pData->bExitPrev = 0;
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if(bInitial)
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{
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InitializeListHead(&pData->leQueue);
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}
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else
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{
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InsertTailList
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(
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&a_leQueues[pData->nPrio],
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&pData->leQueue
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);
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}
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}
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void DoStuff(void)
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{
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unsigned i;
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unsigned n;
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unsigned nId;
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n = rand() % 1000;
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nId = Fbt_GetCurrentId();
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_ftprintf(stderr, _T("[%u] BEGIN\n"), nId);
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for(i = 0; i < n; ++ i)
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{
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unsigned j;
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unsigned m;
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_ftprintf(stderr, _T("[%u] [%u/%u]\n"), nId, i + 1, n);
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m = rand() % 1000;
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for(j = 0; j < m; ++ j)
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Sleep(0);
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Fbt_Yield();
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}
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_ftprintf(stderr, _T("[%u] END\n"), nId);
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}
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int _tmain(int argc, _TCHAR const * const * argv)
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{
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unsigned i;
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unsigned nFibers;
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if(argc > 1)
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nFibers = _tcstoul(argv[1], NULL, 0);
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else
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nFibers = FIBERTEST_COUNT;
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for(i = 0; i < 32; ++ i)
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{
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InitializeListHead(&a_leQueues[i]);
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}
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for(i = 0; i < nFibers; ++ i)
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Fbt_CreateFiber(i == 0);
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Fbt_Startup(GetFiberData());
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return 0;
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}
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/* EOF */
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