code review 10692043: undo CL 9776044 / 1e280889f997

undo CL 9776044 / 1e280889f997

Failure on bot:
http://build.golang.org/log/f4c648906e1289ec2237c1d0880fb1a8b1852a08

««« original CL description
runtime: fix CPU underutilization
runtime.newproc/ready are deliberately sloppy about waking new M's,
they only ensure that there is at least 1 spinning M.
Currently to compensate for that, schedule() checks if the current P
has local work and there are no spinning M's, it wakes up another one.
It does not work if goroutines do not call schedule.
With this change a spinning M wakes up another M when it finds work to do.
It's also not ideal, but it fixes the underutilization.
A proper check would require to know the exact number of runnable G's,
but it's too expensive to maintain.
Fixes issue 5586.

R=rsc
TBR=rsc
CC=gobot, golang-dev
https://codereview.appspot.com/9776044
»»»

[dvyukov, 2013-06-27 17:03:28]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://dvyukov%40google.com@code.google.com/p/go/

[dvyukov, 2013-06-27 17:03:39]

*** Submitted as https://code.google.com/p/go/source/detail?r=4fe0404effd1 ***

undo CL 9776044 / 1e280889f997

Failure on bot:
http://build.golang.org/log/f4c648906e1289ec2237c1d0880fb1a8b1852a08

««« original CL description
runtime: fix CPU underutilization
runtime.newproc/ready are deliberately sloppy about waking new M's,
they only ensure that there is at least 1 spinning M.
Currently to compensate for that, schedule() checks if the current P
has local work and there are no spinning M's, it wakes up another one.
It does not work if goroutines do not call schedule.
With this change a spinning M wakes up another M when it finds work to do.
It's also not ideal, but it fixes the underutilization.
A proper check would require to know the exact number of runnable G's,
but it's too expensive to maintain.
Fixes issue 5586.

R=rsc
TBR=rsc
CC=gobot, golang-dev
https://codereview.appspot.com/9776044
»»»

R=golang-dev
CC=golang-dev
https://codereview.appspot.com/10692043

[r, 2013-06-27 17:12:59]

LGTM