chunks: []ChunkIdx{
				BaseChunkIdx, BaseChunkIdx + 2, BaseChunkIdx + 4, BaseChunkIdx + 6,
				BaseChunkIdx + 8, BaseChunkIdx + 10, BaseChunkIdx + 12, BaseChunkIdx + 14,
				BaseChunkIdx + 16, BaseChunkIdx + 18, BaseChunkIdx + 20, BaseChunkIdx + 22,
				BaseChunkIdx + 24, BaseChunkIdx + 26, BaseChunkIdx + 28, BaseChunkIdx + 30,
				BaseChunkIdx + 32, BaseChunkIdx + 34, BaseChunkIdx + 36, BaseChunkIdx + 38,

				BaseChunkIdx: {{0, 256}},
			},
		},
		"ManyArena": {
			beforeAlloc: map[ChunkIdx][]BitRange{
				BaseChunkIdx:     {{0, PallocChunkPages}},
				BaseChunkIdx + 1: {{0, PallocChunkPages}},
				BaseChunkIdx + 2: {{0, PallocChunkPages - 64}},
			},
			beforeScav: map[ChunkIdx][]BitRange{
				BaseChunkIdx:     {{0, PallocChunkPages}},
				BaseChunkIdx + 1: {{0, PallocChunkPages}},

		si := NewScavengeIndex(BaseChunkIdx, BaseChunkIdx+64)

		// Initialize all the chunks as dense and empty.
		//
		// Also, reset search addresses so that we can get page offsets.
		si.AllocRange(PageBase(BaseChunkIdx, 0), PageBase(BaseChunkIdx+64, 0))
		si.NextGen()
		si.FreeRange(PageBase(BaseChunkIdx, 0), PageBase(BaseChunkIdx+64, 0))
		for ci := BaseChunkIdx; ci < BaseChunkIdx+64; ci++ {
			si.SetEmpty(ci)
		}

		}
	}
}

// BaseChunkIdx is a convenient chunkIdx value which works on both
// 64 bit and 32 bit platforms, allowing the tests to share code
// between the two.
//
// This should not be higher than 0x100*pallocChunkBytes to support
// mips and mipsle, which only have 31-bit address spaces.
var BaseChunkIdx = func() ChunkIdx {
	var prefix uintptr
	if pageAlloc64Bit != 0 {