Comment 2 for bug 1565978

I am going to ask to send the following patch upstream. Let see what the upstream community will say about it

commit 17857791d91cf31944d266cb1dfd9322cea8933f
Author: Breno Leitao <email address hidden>
Date: Mon Apr 4 16:09:55 2016 -0400

    Increase _MaxGomaxprocs to support big machines

    Currently go does not support machines that contains > 256 CPUs, as IBM's E880
    that could host 1536 hardware thread, when configured with 192 CPU cores and
    SMT (Symmetric Multi Thread) 8.

    For example, when running a go program on this machine, I got, the following
    problem[1]:

      procresize: invalid arg

    This is because of the following code:

      _MaxGomaxprocs = 1 << 8

      if old < 0 || old > _MaxGomaxprocs || nprocs <= 0 || nprocs > _MaxGomaxprocs {
          throw("procresize: invalid arg")
      }

    This patch just redefine _MAxGomaxprocs to 1 << 12.

diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index e0137f7..508cecb 100644
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -472,7 +472,7 @@ type p struct {
 const (
  // The max value of GOMAXPROCS.
  // There are no fundamental restrictions on the value.
- _MaxGomaxprocs = 1 << 8
+ _MaxGomaxprocs = 1 << 12
 )

 type schedt struct {