From 14849f0fa57c67996bb00bd42bb14cef9f4e9a1e Mon Sep 17 00:00:00 2001 From: Michael Anthony Knyszek Date: Mon, 12 Aug 2019 22:30:39 +0000 Subject: runtime: add new page allocator constants and description This change is the first of a series of changes which replace the current page allocator (which is based on the contents of mgclarge.go and some of mheap.go) with one based on free/used bitmaps. It adds in the key constants for the page allocator as well as a comment describing the implementation. Updates #35112. Change-Id: I839d3a07f46842ad379701d27aa691885afdba63 Reviewed-on: https://go-review.googlesource.com/c/go/+/190619 Run-TryBot: Michael Knyszek Reviewed-by: Keith Randall Reviewed-by: Austin Clements --- src/runtime/mpagealloc_32bit.go | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 src/runtime/mpagealloc_32bit.go (limited to 'src/runtime/mpagealloc_32bit.go') diff --git a/src/runtime/mpagealloc_32bit.go b/src/runtime/mpagealloc_32bit.go new file mode 100644 index 0000000000..c91b2bbe3f --- /dev/null +++ b/src/runtime/mpagealloc_32bit.go @@ -0,0 +1,23 @@ +// Copyright 2019 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// +build 386 arm mips mipsle wasm darwin,arm64 + +// wasm is a treated as a 32-bit architecture for the purposes of the page +// allocator, even though it has 64-bit pointers. This is because any wasm +// pointer always has its top 32 bits as zero, so the effective heap address +// space is only 2^32 bytes in size (see heapAddrBits). + +// darwin/arm64 is treated as a 32-bit architecture for the purposes of the +// page allocator, even though it has 64-bit pointers and a 33-bit address +// space (see heapAddrBits). The 33 bit address space cannot be rounded up +// to 64 bits because there are too many summary levels to fit in just 33 +// bits. + +package runtime + +const ( + // The number of levels in the radix tree. + summaryLevels = 4 +) -- cgit v1.3