delta/go-git.git/src/runtime/malloc_test.go, branch dev.go2go

runtime: align 12-byte objects to 8 bytes on 32-bit systems

2020-10-01T19:13:03+00:00

Currently on 32-bit systems 8-byte fields in a struct have an alignment
of 4 bytes, which means that atomic instructions may fault. This issue
is tracked in #36606.

Our current workaround is to allocate memory and put any such atomically
accessed fields at the beginning of the object. This workaround fails
because the tiny allocator might not align the object right. This case
specifically only happens with 12-byte objects because a type's size is
rounded up to its alignment. So if e.g. we have a type like:

type obj struct {
    a uint64
    b byte
}

then its size will be 12 bytes, because "a" will require a 4 byte
alignment. This argument may be extended to all objects of size 9-15
bytes.

So, make this workaround work by specifically aligning such objects to 8
bytes on 32-bit systems. This change leaves a TODO to remove the code
once #36606 gets resolved. It also adds a test which will presumably no
longer be necessary (the compiler should enforce the right alignment)
when it gets resolved as well.

Fixes #37262.

Change-Id: I3a34e5b014b3c37ed2e5e75e62d71d8640aa42bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/254057
Reviewed-by: Cherry Zhang 
Reviewed-by: Austin Clements 
Run-TryBot: Cherry Zhang 
TryBot-Result: Go Bot 
Trust: Michael Knyszek

runtime: re-enable TestArenaCollision on darwin in race mode

2020-01-15T17:53:43+00:00

Go 1.14 will drop support for macOS 10.10, see #23011

This reverts CL 155097

Updates #26475
Updates #29340

Change-Id: I64d0275141407313b73068436ee81d13eacc4c76
Reviewed-on: https://go-review.googlesource.com/c/go/+/214058
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

runtime: add per-p page allocation cache

2019-11-08T18:00:54+00:00

This change adds a per-p free page cache which the page allocator may
allocate out of without a lock. The change also introduces a completely
lockless page allocator fast path.

Although the cache contains at most 64 pages (and usually less), the
vast majority (85%+) of page allocations are exactly 1 page in size.

Updates #35112.

Change-Id: I170bf0a9375873e7e3230845eb1df7e5cf741b78
Reviewed-on: https://go-review.googlesource.com/c/go/+/195701
Run-TryBot: Michael Knyszek 
Reviewed-by: Austin Clements

runtime: remove old page allocator

2019-11-08T00:07:43+00:00

This change removes the old page allocator from the runtime.

Updates #35112.

Change-Id: Ib20e1c030f869b6318cd6f4288a9befdbae1b771
Reviewed-on: https://go-review.googlesource.com/c/go/+/195700
Run-TryBot: Michael Knyszek 
TryBot-Result: Gobot Gobot 
Reviewed-by: Austin Clements

runtime: integrate new page allocator into runtime

2019-11-07T20:14:02+00:00

This change integrates all the bits and pieces of the new page allocator
into the runtime, behind a global constant.

Updates #35112.

Change-Id: I6696bde7bab098a498ab37ed2a2caad2a05d30ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/201764
Run-TryBot: Michael Knyszek 
TryBot-Result: Gobot Gobot 
Reviewed-by: Austin Clements

runtime: disable TestArenaCollision on Darwin in race mode

2018-12-19T19:34:50+00:00

This change disables the test TestArenaCollision on Darwin in race mode
to deal with the fact that Darwin 10.10 must use MAP_FIXED in race mode
to ensure we retain our heap in a particular portion of the address
space which the race detector needs. The test specifically checks to
make sure a manually mapped region's space isn't re-used, which is
definitely possible with MAP_FIXED because it replaces whatever mapping
already exists at a given address.

This change then also makes it so that MAP_FIXED is only used in race
mode and on Darwin, not all BSDs, because using MAP_FIXED breaks this
test for FreeBSD in addition to Darwin.

Updates #26475.
Fixes #29340.

Change-Id: I1c59349408ccd7eeb30c4bf2593f48316b23ab2f
Reviewed-on: https://go-review.googlesource.com/c/155097
Run-TryBot: Michael Knyszek 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

runtime: add physical memory scavenging test

2018-10-30T15:44:23+00:00

This change introduces a test to malloc_test which checks for overuse
of physical memory in the large object treap. Due to fragmentation,
there may be many pages of physical memory that are sitting unused in
large-object space.

For #14045.

Change-Id: I3722468f45063b11246dde6301c7ad02ae34be55
Reviewed-on: https://go-review.googlesource.com/c/138918
Run-TryBot: Michael Knyszek 
TryBot-Result: Gobot Gobot 
Reviewed-by: Austin Clements

runtime: only run TestMemStats sanity tests once

2018-07-09T17:48:35+00:00

Fixes #22696

Change-Id: Ibe4628f71d64a2b36b655ea69710a925924b12a3
Reviewed-on: https://go-review.googlesource.com/122586
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick 
Reviewed-by: Austin Clements

runtime: stop when we run out of hints in race mode

2018-04-04T18:08:04+00:00

Currently, the runtime falls back to asking for any address the OS can
offer for the heap when it runs out of hint addresses. However, the
race detector assumes the heap lives in [0x00c000000000,
0x00e000000000), and will fail in a non-obvious way if we go outside
this region.

Fix this by actively throwing a useful error if we run out of heap
hints in race mode.

This problem is currently being triggered by TestArenaCollision, which
intentionally triggers this fallback behavior. Fix the test to look
for the new panic message in race mode.

Fixes #24670.
Updates #24133.

Change-Id: I57de6d17a3495dc1f1f84afc382cd18a6efc2bf7
Reviewed-on: https://go-review.googlesource.com/104717
Run-TryBot: Austin Clements 
Reviewed-by: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot

runtime: only run TestArenaCollision if the target can exec

2018-02-16T15:33:42+00:00

Replace the test for nacl with testenv.MustHaveExec to also skip
test on iOS.

Change-Id: I6822714f6d71533d1b18bbb7894f6ad339d8aea1
Reviewed-on: https://go-review.googlesource.com/94755
Run-TryBot: Elias Naur 
TryBot-Result: Gobot Gobot 
Reviewed-by: Austin Clements