code review 11796043: [release-branch.go1.1] runtime: prevent sysmon from pol...

[release-branch.go1.1] runtime: prevent sysmon from polling network excessively

This is a manual application of the following CL.

««« CL 11569043 / 6b3c351c7fe6
runtime: prevent sysmon from polling network excessivly
If the network is not polled for 10ms, sysmon starts polling network
on every iteration (every 20us) until another thread blocks in netpoll.
Fixes   issue 5922  .

R=golang-dev, iant
CC=golang-dev
https://codereview.appspot.com/11569043
»»»

Update issue 5928

[adg, 2013-07-24 23:10:50]

Hello dvyukov@google.com, rsc@golang.org (cc: golang-dev@googlegroups.com),

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

[dvyukov, 2013-07-25 08:48:00]

LGTM

[dvyukov, 2013-07-25 08:53:42]

On 2013/07/25 08:48:00, dvyukov wrote:
> LGTM

although I need to admit that I have more and more worries:
 - we never had a user bug report for this
 - we don't have a reproducer
 - this is new code in release branch

drop it?

[dave_cheney.net, 2013-07-25 08:55:27]

Is there some way I can observe the before and after behaviour? ie, is
it visible in strace ?

On Thu, Jul 25, 2013 at 6:53 PM,  <dvyukov@google.com> wrote:
> On 2013/07/25 08:48:00, dvyukov wrote:
>>
>> LGTM
>
>
> although I need to admit that I have more and more worries:
>  - we never had a user bug report for this
>  - we don't have a reproducer
>  - this is new code in release branch
>
> drop it?
>
>
> https://codereview.appspot.com/11796043/
>
> --
>
> ---You received this message because you are subscribed to the Google Groups
> "golang-dev" group.
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>
>

[dvyukov, 2013-07-25 09:03:20]

On Thu, Jul 25, 2013 at 12:55 PM, Dave Cheney <dave@cheney.net> wrote:
> Is there some way I can observe the before and after behaviour? ie, is
> it visible in strace ?


Well, if you have a reproducer, you must observe lots of calls to
epollwait() every 20us.


> On Thu, Jul 25, 2013 at 6:53 PM,  <dvyukov@google.com> wrote:
>> On 2013/07/25 08:48:00, dvyukov wrote:
>>>
>>> LGTM
>>
>>
>> although I need to admit that I have more and more worries:
>>  - we never had a user bug report for this
>>  - we don't have a reproducer
>>  - this is new code in release branch
>>
>> drop it?
>>
>>
>> https://codereview.appspot.com/11796043/
>>
>> --
>>
>> ---You received this message because you are subscribed to the Google Groups
>> "golang-dev" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to golang-dev+unsubscribe@googlegroups.com.
>> For more options, visit https://groups.google.com/groups/opt_out.
>>
>>

[adg, 2013-07-25 23:15:53]

*** Abandoned ***

[adg, 2013-07-25 23:16:13]

On 25 July 2013 18:53, <dvyukov@google.com> wrote:

> On 2013/07/25 08:48:00, dvyukov wrote:
>
>> LGTM
>>
>
> although I need to admit that I have more and more worries:
>  - we never had a user bug report for this
>  - we don't have a reproducer
>  - this is new code in release branch
>
> drop it?
>

SGTM