runtime/trace: also treat plan9 as a low memory system

Fixes #31554
Updates #12032 (also originally about plan9, but later openbsd/arm)

Change-Id: Ib9f35d27a2304f38bf271c38c0b9153d210d8f95
Reviewed-on: https://go-review.googlesource.com/c/go/+/172837
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/runtime/trace/trace_test.go b/src/runtime/trace/trace_test.go
index fc81abc30ff25ac026bfe0546f2593dc972e08d9..e289fa5e12a6a14de888983866f844557e641d81 100644 (file)
--- a/src/runtime/trace/trace_test.go
+++ b/src/runtime/trace/trace_test.go
@@ -237,7 +237,7 @@ func TestTraceStress(t *testing.T) {
        runtime.GC()
        // Trigger GC from malloc.
        n := int(1e3)
-       if runtime.GOOS == "openbsd" && runtime.GOARCH == "arm" {
+       if isMemoryConstrained() {
                // Reduce allocation to avoid running out of
                // memory on the builder - see issue/12032.
                n = 512
@@ -322,6 +322,21 @@ func TestTraceStress(t *testing.T) {
        testBrokenTimestamps(t, trace)
 }
 
+// isMemoryConstrained reports whether the current machine is likely
+// to be memory constrained.
+// This was originally for the openbsd/arm builder (Issue 12032).
+// TODO: move this to testenv? Make this look at memory? Look at GO_BUILDER_NAME?
+func isMemoryConstrained() bool {
+       if runtime.GOOS == "plan9" {
+               return true
+       }
+       switch runtime.GOARCH {
+       case "arm", "mips", "mipsle":
+               return true
+       }
+       return false
+}
+
 // Do a bunch of various stuff (timers, GC, network, etc) in a separate goroutine.
 // And concurrently with all that start/stop trace 3 times.
 func TestTraceStressStartStop(t *testing.T) {
@@ -381,9 +396,9 @@ func TestTraceStressStartStop(t *testing.T) {
                runtime.GC()
                // Trigger GC from malloc.
                n := int(1e3)
-               if runtime.GOOS == "openbsd" && runtime.GOARCH == "arm" {
+               if isMemoryConstrained() {
                        // Reduce allocation to avoid running out of
-                       // memory on the builder - see issue/12032.
+                       // memory on the builder.
                        n = 512
                }
                for i := 0; i < n; i++ {