Re: [PATCH] Autotune swappiness

[Con Kolivas <kernel@kolivas.org>]

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Martin J. Bligh wrote:
>>>>Here is another try at providing feedback to tune the vm_swappiness.
>>>
>>>
>>>I spent some time yesterday trying to demonstrate performance improvements
>>>from those two patches.  Using
>>>
>>>	make -j4 vmlinux with mem=64m
>>>
>>>and
>>>
>>>	qsbench -p 4 -m 96 with mem=256m
>>>
>>>and was not able to do so, which is what I expected.
>>>
>>>We do need more quantitative testing on this work.
>>
>>Sure thing.
>>
>>I need to point out a few things:
>>The point of this patch was to improve the swap behaviour on desktop like loads.
>>The fact that it improved the "when swap is thrashing" scenario (in my testing) was an unintentional bonus.
>>I dont think your load of j4 will induce quite the same swap thrash as what I was testing. I actually suspect the faster cpu & more jobs over fixed memory shows it more.
>>I need someone with more varied hardware to test it for me. I can recreate equivalent results on my current machine which has similar hardware, but I think results showing improvement on different machines   and different loads is what you're looking for... and since I'm currently quite low on hardware I can only offer results from this one (and my wife is hating it being offline o_0)
>>
>>Anyone willing to offer to do some tests?
> 
> 
> What kind of mem pressure are you looking for? kernel compile is easy to run, 
> and straight "-j" should kill a small system fairly well ... you want it just
> into swap, or thrashing the crap out of it?

It was coincidental that it helped the swap thash scenario. But yes, 
thrashing the crap out of it. Maybe taking 5-10 times longer than when 
there's enough memory for the job.

Con

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