[ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[Peter Williams]

PlugSched-5.2.1 is available for 2.6.11 and 2.6.12 kernels.  This 
version applies Con Kolivas's latest modifications to his "nice" aware 
SMP load balancing patches.

A patch to bring PlugSched-5.2 for 2.6.11 to PlugSched-5.2.1 is 
available at:

<http://prdownloads.sourceforge.net/cpuse/plugsched-5.2-to-5.2.1-for-2.6.11.patch?download>

A patch for 2.6.12 is available at:

<http://prdownloads.sourceforge.net/cpuse/plugsched-5.2.1-for-2.6.12.patch?download>

Very Brief Documentation:

You can select a default scheduler at kernel build time.  If you wish to
boot with a scheduler other than the default it can be selected at boot
time by adding:

cpusched=<scheduler>

to the boot command line where <scheduler> is one of: ingosched,
nicksched, staircase, spa_no_frills or zaphod.  If you don't change the
default when you build the kernel the default scheduler will be
ingosched (which is the normal scheduler).

The scheduler in force on a running system can be determined by the
contents of:

/proc/scheduler

Control parameters for the scheduler can be read/set via files in:

/sys/cpusched/<scheduler>/

Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce

Re: [ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[Con Kolivas]

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On Mon, 20 Jun 2005 15:33, Peter Williams wrote:
> PlugSched-5.2.1 is available for 2.6.11 and 2.6.12 kernels.  This
> version applies Con Kolivas's latest modifications to his "nice" aware
> SMP load balancing patches.

Thanks Peter. 

Any word from your own testing/testers on how well smp nice balancing is 
working for them now? 

Cheers,
Con

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Re: [ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[Peter Williams]

Con Kolivas wrote:
> On Mon, 20 Jun 2005 15:33, Peter Williams wrote:
> 
>>PlugSched-5.2.1 is available for 2.6.11 and 2.6.12 kernels.  This
>>version applies Con Kolivas's latest modifications to his "nice" aware
>>SMP load balancing patches.
> 
> 
> Thanks Peter. 
> 
> Any word from your own testing/testers on how well smp nice balancing is 
> working for them now? 

No, they got side tracked onto something else but should start working 
on it again soon.  I'll give them a prod :-)

Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce

Re: [ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[Peter Williams]

Peter Williams wrote:
> Con Kolivas wrote:
> 
>> On Mon, 20 Jun 2005 15:33, Peter Williams wrote:
>>
>>> PlugSched-5.2.1 is available for 2.6.11 and 2.6.12 kernels.  This
>>> version applies Con Kolivas's latest modifications to his "nice" aware
>>> SMP load balancing patches.
>>
>>
>>
>> Thanks Peter.
>> Any word from your own testing/testers on how well smp nice balancing 
>> is working for them now? 
> 
> 
> No, they got side tracked onto something else but should start working 
> on it again soon.  I'll give them a prod :-)

Con,
	We've done some more testing with this with results that are still 
disappointing.  We think that one reason for this is that move_tasks() 
doesn't take "nice" into account.  I'm going to look at modifying it so 
that it moves a certain amount of niceness rather than a specified 
number of tasks.
	A second (more difficult to solve) issue is that we think it would work 
better if both queue lengths and "nice" loads were kept approximately 
equal between the queues.  It's hard to see how this can be managed 
without considerable overhead.

Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce

Re: [ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[Con Kolivas]

On Tue, 5 Jul 2005 17:46, Peter Williams wrote:
> Peter Williams wrote:
> > Con Kolivas wrote:
> >> On Mon, 20 Jun 2005 15:33, Peter Williams wrote:
> >>> PlugSched-5.2.1 is available for 2.6.11 and 2.6.12 kernels.  This
> >>> version applies Con Kolivas's latest modifications to his "nice" aware
> >>> SMP load balancing patches.
> >>
> >> Thanks Peter.
> >> Any word from your own testing/testers on how well smp nice balancing
> >> is working for them now?
> >
> > No, they got side tracked onto something else but should start working
> > on it again soon.  I'll give them a prod :-)
>
> Con,
> 	We've done some more testing with this with results that are still
> disappointing. 

Is this with the migration thread accounted patch as well?

Con

Re: [ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[Peter Williams]

Con Kolivas wrote:
> On Tue, 5 Jul 2005 17:46, Peter Williams wrote:
> 
>>Peter Williams wrote:
>>
>>>Con Kolivas wrote:
>>>
>>>>On Mon, 20 Jun 2005 15:33, Peter Williams wrote:
>>>>
>>>>>PlugSched-5.2.1 is available for 2.6.11 and 2.6.12 kernels.  This
>>>>>version applies Con Kolivas's latest modifications to his "nice" aware
>>>>>SMP load balancing patches.
>>>>
>>>>Thanks Peter.
>>>>Any word from your own testing/testers on how well smp nice balancing
>>>>is working for them now?
>>>
>>>No, they got side tracked onto something else but should start working
>>>on it again soon.  I'll give them a prod :-)
>>
>>Con,
>>	We've done some more testing with this with results that are still
>>disappointing. 
> 
> 
> Is this with the migration thread accounted patch as well?

Yes.

-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce

Re: [ANNOUNCE][RFC] PlugSched-5.2.1 for 2.6.11 and 2.6.12

[Con Kolivas]

On Tue, 5 Jul 2005 21:25, Peter Williams wrote:
> Con Kolivas wrote:
> > On Tue, 5 Jul 2005 17:46, Peter Williams wrote:
> >>Peter Williams wrote:
> >>>Con Kolivas wrote:
> >>>>On Mon, 20 Jun 2005 15:33, Peter Williams wrote:
> >>>>>PlugSched-5.2.1 is available for 2.6.11 and 2.6.12 kernels.  This
> >>>>>version applies Con Kolivas's latest modifications to his "nice" aware
> >>>>>SMP load balancing patches.
> >>>>
> >>>>Thanks Peter.
> >>>>Any word from your own testing/testers on how well smp nice balancing
> >>>>is working for them now?
> >>>
> >>>No, they got side tracked onto something else but should start working
> >>>on it again soon.  I'll give them a prod :-)
> >>
> >>Con,
> >>	We've done some more testing with this with results that are still
> >>disappointing.
> >
> > Is this with the migration thread accounted patch as well?

The results from smp nice I've received so far show that a 30% slowdown 
(instead of 5% on uniprocessor) occurs to high priority tasks in the presence 
of low priority tasks worst case scenario when the tasks sleep frequently. 
However excellent smp nice support with negligible slowdown occurs (ie nice 
is well respected) when the tasks are fully cpu bound. This suggests that 
what is happening on task wakeup is the limiting factor with this smp nice 
implementation. This makes sense given that most of the balancing occurs 
during busy rebalance when the queues are busy. I tried ignoring the length 
of queue (ie not having the single task running check for idle rebalance) and 
while this improved the nice effect substantially, it also cost us heavily in 
throughput making it unwarranted.

Cheers,
Con