On Wed, Nov 21, 2012 at 07:21:58PM +0100, Ingo Molnar wrote:

* Mel Gorman [off-list ref] wrote:

quoted

On Wed, Nov 21, 2012 at 06:33:16PM +0100, Ingo Molnar wrote:

quoted

* Mel Gorman [off-list ref] wrote:

quoted

On Wed, Nov 21, 2012 at 06:03:06PM +0100, Ingo Molnar wrote:

quoted

* Mel Gorman [off-list ref] wrote:

quoted

On Wed, Nov 21, 2012 at 10:21:06AM +0000, Mel Gorman wrote:

quoted

I am not including a benchmark report in this but will be posting one
shortly in the "Latest numa/core release, v16" thread along with the latest
schednuma figures I have available.

Report is linked here https://lkml.org/lkml/2012/11/21/202

I ended up cancelling the remaining tests and restarted with

1. schednuma + patches posted since so that works out as

Mel, I'd like to ask you to refer to our tree as numa/core or 
'numacore' in the future. Would such a courtesy to use the 
current name of our tree be possible?

Sure, no problem.

Thanks!

I ran a quick test with your 'balancenuma v4' tree and while 
numa02 and numa01-THREAD-ALLOC performance is looking good, 
numa01 performance does not look very good:

                    mainline    numa/core      balancenuma-v4
     numa01:           340.3       139.4          276 secs

97% slower than numa/core.

It would be. numa01 is an adverse workload where all threads 
are hammering the same memory.  The two-stage filter in 
balancenuma restricts the amount of migration it does so it 
ends up in a situation where it cannot balance properly. [...]

Do you mean this "balancenuma v4" patch attributed to you:

 Subject: mm: Numa: Use a two-stage filter to restrict pages being migrated for unlikely task<->node relationships
 From: Mel Gorman [off-list ref]
 Date: Wed, 21 Nov 2012 10:21:42 +0000

Yes.

 ...

 Signed-off-by: Mel Gorman [off-list ref]

which has:

                /*
                 * Multi-stage node selection is used in conjunction
                 * with a periodic migration fault to build a temporal
                 * task<->page relation. By using a two-stage filter we
                 * remove short/unlikely relations.
                 *
                 * Using P(p) ~ n_p / n_t as per frequentist
                 * probability, we can equate a task's usage of a
                 * particular page (n_p) per total usage of this
                 * page (n_t) (in a given time-span) to a probability.
                 *
                 * Our periodic faults will sample this probability and
                 * getting the same result twice in a row, given these
                 * samples are fully independent, is then given by
                 * P(n)^2, provided our sample period is sufficiently
                 * short compared to the usage pattern.
                 *
                 * This quadric squishes small probabilities, making
                 * it less likely we act on an unlikely task<->page
                 * relation.

This looks very similar to the code and text that Peter wrote 
for numa/core:

/*
 * Multi-stage node selection is used in conjunction with a periodic
 * migration fault to build a temporal task<->page relation. By
 * using a two-stage filter we remove short/unlikely relations.
 *
 * Using P(p) ~ n_p / n_t as per frequentist probability, we can
 * equate a task's usage of a particular page (n_p) per total usage
 * of this page (n_t) (in a given time-span) to a probability.
 *
 * Our periodic faults will then sample this probability and getting
 * the same result twice in a row, given these samples are fully
 * independent, is then given by P(n)^2, provided our sample period
 * is sufficiently short compared to the usage pattern.
 *
 * This quadric squishes small probabilities, making it less likely
 * we act on an unlikely task<->page relation.
 *
 * Return the best node ID this page should be on, or -1 if it should
 * stay where it is.
 */

see commit:

  30f93abc6cb3 sched, numa, mm: Add the scanning page fault machinery

?

I think it's the very same concept - yours is taken from an 
older sched/numa commit and attributed to yourself? [If so then 
please fix the attribution.]

Yes, it's completely based on earlier sched/numa patches. In many of the
patches you'll see notes where I documented what patches I originally
based on -- be it from sched/numa, autonuma or some combination of both.
In many cases I could not keep the signed-off-by because the end result
was simply too different to claim that the author was happy with it. I was
hoping that these notes would convert to signed-offs-by after review from
the original authors who were cc'd at all times.

We have the same filter in numa/core - because we wrote it (FYI, 
I wrote bits of the last_cpu variant in numa/core), yet our 
numa01 performance is much better than the one of balancenuma.

Yes, the lack of a note was a mistake. I've added the following note to
the top of this patch now

Note: This two-stage filter was taken directly from the sched/numa patch
        "sched, numa, mm: Add the scanning page fault machinery" but is
        only a partial extraction. As the end result is not necessarily
        recognisable, the signed-offs-by had to be removed. Will be
        added back if requested.

Thanks and apologies in advance for any other patch where I failed to
document the history correctly.

-- 
Mel Gorman
SUSE Labs

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