From bd6aeca9686d5e672ffda1ea0cfeac7a3e7a20a4 Mon Sep 17 00:00:00 2001 From: Michael Anthony Knyszek Date: Mon, 16 Nov 2020 21:57:32 +0000 Subject: runtime: prepare arenas for use incrementally This change moves the call of sysMap from (*mheap).sysAlloc into (*mheap).grow, so we only sysMap what we're going to use in the near future (thanks to the curArena mechanism). The purpose of this change is to better support systems with strict overcommit rules which generally accept reserved memory but not prepared memory (see malloc.go for exact descriptions of these states). This move requires changing linearAlloc to only optionally map memory. In one case, with mheap.heapArenaAlloc, we do want it to map memory. But now in the other case, with mheap.arena, we don't, because we want grow to take care of it. The risk with this change is we may make more syscalls than before on systems with 64 MiB arenas, but because heap growth is relatively rare this is unlikely to be a noticable issue. We also bound the amount of syscalls made by only extending curArena (and thus mapping) by pallocChunkPages*pageSize which is 4 MiB. Fixes #42612. Change-Id: I736df696afe78ddb1a747a896caa0db8726027e5 Reviewed-on: https://go-review.googlesource.com/c/go/+/270537 Trust: Michael Knyszek Run-TryBot: Michael Knyszek TryBot-Result: Go Bot Reviewed-by: Michael Pratt --- src/runtime/export_test.go | 3 --- 1 file changed, 3 deletions(-) (limited to 'src/runtime/export_test.go') diff --git a/src/runtime/export_test.go b/src/runtime/export_test.go index 195b7b0519..c03cf136f2 100644 --- a/src/runtime/export_test.go +++ b/src/runtime/export_test.go @@ -404,9 +404,6 @@ func ReadMemStatsSlow() (base, slow MemStats) { slow.HeapReleased += uint64(pg) * pageSize } - // Unused space in the current arena also counts as released space. - slow.HeapReleased += uint64(mheap_.curArena.end - mheap_.curArena.base) - getg().m.mallocing-- }) -- cgit v1.3-5-g9baa