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0e6aecdbb8
arenavm.c -- move chunk-return into new function "VMCompact". (also, in VMArenaFinish, null out arena->primary in VMArenaFinish, so it is not left dangling). arena.c, arenavm.c, mpm.h, mpmst.h, mpmtypes.h: arena->class->compact: ArenaCompact, ArenaTrivCompact, VMCompact trace.c -- traceReclaim calls ArenaCompact! Copied from Perforce Change: 170095 ServerID: perforce.ravenbrook.com
90 lines
2.2 KiB
Text
90 lines
2.2 KiB
Text
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================ NOTES; CONSIDER ADDING THESE TO DESIGN DOCS ==================
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____PRIMARY____
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The primary chunk is used specially:
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1. Arenacl requires a chunk to store the ArenaStruct in. (Whereas arenavm gets storage by simply mapping a new page). Therefore destroying the primary chunk would (in general) destroy the arena.
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2. there's a field arena->primary that stores a pointer to the primary chunk. If the primary chunk ever goes away (eg. at ArenaFinish), this pointer must be nulled out so it is not left dangling.
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3. PageSize is known by chunks, not the arena. When arena needs to know page size, it asks the primary chunk.
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4. Various *Check functions only bother to check the primary chunk, and ignore other chunks.
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______NOTES ON CHUNK_CREATE________
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VMArenaInit
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VMChunkCreate
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vmArenaExtend
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VMChunkCreate
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VMChunkCreate [arenavm.c]
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VMCreate [
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- normal:
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Create
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alloc
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Init
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<class>Init
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- arena:
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ACreate
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VMAInit
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alloc VMAS, contains AS
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AInit
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init AS fields
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init VMAS fields
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- AS and VMAS fields are set
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VMChunkCreate
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VMCreate(size) - alloc big chunk of vmem!
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BootBlockInit
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alloc(VMChunkStruct) (contains ChunkStruct)
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map(VMChunkStruct)
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ChunkInit
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ChunkStruct fields
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RingAppend(&arena->chunkRing, &chunk->chunkRing)
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alloc(aBPageIsAllocated "allocTable")
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VMChunkInit
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alloc(aBPSGIsMapped "pageTableMapped")
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alloc(aBPSGHasNoSpares "noSparePages")
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map(up to here)
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res(pTM)
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res(nSP)
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alloc(aPS "pageTable")
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allocBase = iPageFirstUseable
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res(aT)
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sig(Chunk)
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sig(VMChunk)
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primary = chunk
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zoneShift = SizeFloorLog2(chunkSize >> MPS_WORD_SHIFT);
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alignment = ChunkPageSize(arena->primary)
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ChunkEncache(arena, arena->primary);
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--- chunk contents:
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VMChunkStruct (contains ChunkStruct)
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aBPageIsAllocated "allocTable"
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- 1 PSG (PageStructGroup) fits into 1 page
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aBPSGIsMapped "pageTableMapped"
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aBPSGHasNoSpares "noSparePages"
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(...memory up to here is always mapped)
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aPS "pageTable"
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- iPageFirstUseable "allocBase" is here
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---
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$Id$
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