private unsafe void FindDestinationArea(ref UIntPtr destPage, ref UIntPtr destCursor, ref UIntPtr destLimit, UIntPtr objectSize, PageType destGeneration) { VTable.Assert(IsValidGeneration((int)destGeneration)); UIntPtr cursorPage = PageTable.Page(destCursor); UIntPtr limitPage = PageTable.Page(destLimit); UIntPtr pageAddr = PageTable.PagePad(destCursor); UIntPtr testPage = limitPage; UIntPtr endTestPage = PageTable.PageCount(destCursor + objectSize); if (destCursor > UIntPtr.Zero && IsMyZombiePage(PageTable.Page(destCursor - 1))) { VTable.Assert(destPage == limitPage); while (IsMyZombiePage(testPage) || (testPage < endTestPage && (PageTable.IsUnusedPage(testPage)))) { testPage++; } if (testPage >= endTestPage) { // We can expand the current region endTestPage = testPage; VTable.Assert(PageTable.PageAligned(destLimit)); InteriorPtrTable.ClearFirst(limitPage, testPage); if (GC.remsetType == RemSetType.Cards) { OffsetTable.ClearLast(PageTable.PageAddr(limitPage), PageTable.PageAddr(testPage) - 1); } while (limitPage != endTestPage) { VTable.Assert(PageTable.IsUnusedPage(destPage)); do { destPage++; } while (destPage < endTestPage && PageTable.IsUnusedPage(destPage)); bool fCleanPages = true; bool status = PageManager.TryReserveUnusedPages(null, limitPage, destPage - limitPage, nurseryGeneration, ref fCleanPages); VTable.Assert(status); MakeZombiePages(limitPage, destPage - limitPage, destGeneration); while (destPage < endTestPage && IsMyZombiePage(destPage)) { destPage++; } limitPage = destPage; } destLimit = PageTable.PageAddr(limitPage); return; } } if (destCursor != pageAddr) { cursorPage++; } if (cursorPage != limitPage) { this.RegisterSkippedPages(cursorPage, limitPage); } // Find new region big enough to contain object UIntPtr neededPages = PageTable.PageCount(objectSize); UIntPtr prefixPage; while (true) { do { destPage++; } while (!IsMyZombiePage(destPage)); cursorPage = destPage; prefixPage = cursorPage; do { destPage++; } while (IsMyZombiePage(destPage)); limitPage = destPage; if (neededPages <= limitPage - cursorPage) { break; } // Check for following unused pages endTestPage = cursorPage + neededPages; VTable.Assert(endTestPage <= PageTable.pageTableCount); while (destPage < endTestPage && (PageTable.IsUnusedPage(destPage) || (IsMyZombiePage(destPage)))) { destPage++; } if (destPage == endTestPage) { break; } // Check for preceding unused pages if (destPage >= neededPages) { endTestPage = destPage - neededPages; prefixPage = cursorPage - 1; while (prefixPage >= UIntPtr.Zero && PageTable.IsUnusedPage(prefixPage)) { prefixPage--; } prefixPage++; if (prefixPage == endTestPage) { break; } } // Register any skipped regions of pages this.RegisterSkippedPages(cursorPage, limitPage); while (limitPage < destPage) { VTable.Assert(PageTable.IsUnusedPage(limitPage)); do { limitPage++; } while (limitPage < destPage && PageTable.IsUnusedPage(limitPage)); cursorPage = limitPage; while (limitPage < destPage && IsMyZombiePage(limitPage)) { limitPage++; } if (cursorPage != limitPage) { this.RegisterSkippedPages(cursorPage, limitPage); } } } // We found an area big enough. Commit the pre- and // postfix areas of unused pages if (prefixPage != cursorPage) { bool fCleanPages = true; bool status = PageManager.TryReserveUnusedPages(null, prefixPage, cursorPage - prefixPage, nurseryGeneration, ref fCleanPages); VTable.Assert(status); MakeZombiePages(prefixPage, cursorPage - prefixPage, destGeneration); } while (destPage != limitPage) { // Mark the region of unused pages as fromspace UIntPtr unusedPage = limitPage; VTable.Assert(PageTable.IsUnusedPage(unusedPage)); do { unusedPage++; } while (unusedPage < destPage && PageTable.IsUnusedPage(unusedPage)); bool fCleanPages = true; bool status = PageManager.TryReserveUnusedPages(null, limitPage, unusedPage - limitPage, nurseryGeneration, ref fCleanPages); VTable.Assert(status); MakeZombiePages(limitPage, unusedPage - limitPage, destGeneration); // Skip any sections of pages already marked as fromspace limitPage = unusedPage; while (limitPage < destPage && IsMyZombiePage(limitPage)) { limitPage++; } } destCursor = PageTable.PageAddr(prefixPage); destLimit = PageTable.PageAddr(limitPage); // Take ownership of the new pages InteriorPtrTable.ClearFirst(prefixPage, limitPage); InteriorPtrTable.SetFirst(destCursor + PreHeader.Size); if (GC.remsetType == RemSetType.Cards) { OffsetTable.ClearLast(PageTable.PageAddr(prefixPage), PageTable.PageAddr(limitPage) - 1); } }
private UIntPtr ExtendAlloc(UIntPtr bytes, uint alignment, Thread currentThread) { if (this.reserveLimit == UIntPtr.Zero) { return(UIntPtr.Zero); } #if SINGULARITY_KERNEL Kernel.Waypoint(700); #endif UIntPtr neededBytes = bytes + // Bytes required for object + alignment - UIntPtr.Size - // worst case alignment overhead + (this.reserveLimit - this.allocPtr); // bytes already available UIntPtr paddedNeed = PageTable.PagePad(neededBytes); UIntPtr pageCount = PageTable.PageCount(paddedNeed); UIntPtr startPage = PageTable.Page(this.reserveLimit); bool fCleanPages = CLEAR_POOL_PAGES(); bool gotPages = PageManager.TryReserveUnusedPages(currentThread, startPage, pageCount, this.pageType, ref fCleanPages); if (!gotPages) { // We can't indiscriminately ask for more memory if we have // unused pages already available. return(UIntPtr.Zero); } if (this.reserveLimit == UIntPtr.Zero) { // A collection occurred, so there is no region to extend PageManager.ReleaseUnusedPages(startPage, pageCount, fCleanPages); return(UIntPtr.Zero); } BaseCollector.IncrementNewBytesSinceGC(paddedNeed); this.allocNew = this.reserveLimit; // Pad alignment space if necessary. NB: a prior call to // AllocateFast may have started generating alignment tokens, // but we may need to finish the job here if the residual space // was insufficient for a multi-word alignment. UIntPtr oldReserveLimit = this.reserveLimit; this.reserveLimit += paddedNeed; this.allocPtr = Allocator.AlignedAllocationPtr(this.allocPtr, this.reserveLimit, alignment); if (this.zeroedLimit < this.allocPtr) { this.zeroedLimit = this.allocPtr; } UIntPtr objectAddr = this.allocPtr + PreHeader.Size; this.allocPtr += bytes; if (fCleanPages) { if (this.zeroedLimit < oldReserveLimit) { Util.MemClear(this.zeroedLimit, oldReserveLimit - this.zeroedLimit); } this.zeroedLimit = this.reserveLimit; } else { Util.MemClear(this.zeroedLimit, this.allocPtr - this.zeroedLimit); this.zeroedLimit = this.allocPtr; } VTable.Assert(this.allocPtr <= this.zeroedLimit); VTable.Assert(PageTable.PageAligned(this.reserveLimit)); if (objectAddr >= oldReserveLimit) { // Object is first on new page InteriorPtrTable.SetFirst(objectAddr); } else if (objectAddr + bytes < this.reserveLimit) { // The object does not end on new limit // N.B. The next object may not be allocated at exactly // (objectAddr + bytes) due to alignment considerations. It // also might not ever be allocated. These cases are handled // by InteriorPtrTable.First skipping over alignment tokens // and callers of First watching out for unused space tokens. InteriorPtrTable.SetFirst(objectAddr + bytes); } // We know an object is located as the last one in a page // when it extends through the page to the next. // Otherwise, it is totally before or below the page, and // we are not sure whether it is the last object or not. // So record only such an object for the last card in that // page. Many objects may have been omitted due to // this coarse-grain recording. But we should be able // to incrementally update the offset table and find them. // I believe this is a better choice than simply recording // any object to the offset table, because most objects // may just die and need not to record. #if !SINGULARITY || SEMISPACE_COLLECTOR || ADAPTIVE_COPYING_COLLECTOR || SLIDING_COLLECTOR if (GC.remsetType == RemSetType.Cards) { if (objectAddr < oldReserveLimit && allocPtr + bytes > oldReserveLimit) { #if DONT_RECORD_OBJALLOC_IN_OFFSETTABLE #else OffsetTable.SetLast(objectAddr); #endif } } #endif #if SINGULARITY_KERNEL Kernel.Waypoint(701); #endif return(objectAddr); }