runtime: increase MaxGomaxprocs to 1024

Currently MaxGomaxprocs is 256. The previous CL saved enough per-P
static space that we can quadruple MaxGomaxprocs (and hence the static
size of allp) and still come out ahead.

This is safe for Go 1.9. In Go 1.10 we'll eliminate the hard-coded
limit entirely.

Updates #15131.

Change-Id: I919ea821c1ce64c27812541dccd7cd7db4122d16
Reviewed-on: https://go-review.googlesource.com/45673
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index da57235b0276f570891bd6a09c5acd6dada449d5..2df1fefe7cd861f6fed14c185425a1039b75717e 100644 (file)
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -518,7 +518,7 @@ type p struct {
 const (
        // The max value of GOMAXPROCS.
        // There are no fundamental restrictions on the value.
-       _MaxGomaxprocs = 1 << 8
+       _MaxGomaxprocs = 1 << 10
 )
 
 type schedt struct {