linux-kernel - Re: UKSM: What's maintainers think about it?

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Date:	Wed, 29 Oct 2014 00:36:14 +0300
From:	Timofey Titovets <nefelim4ag@...il.com>
To:	Marco A Benatto <marco.benatto@...driva.com.br>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: UKSM: What's maintainers think about it?

2014-10-28 20:40 GMT+03:00 Marco A Benatto <marco.benatto@...driva.com.br>:
> On Tue, Oct 28, 2014 at 04:59:45PM +0300, Timofey Titovets wrote:
>> 2014-10-28 16:31 GMT+03:00 Marco A Benatto <marco.benatto@...driva.com.br>:
>> > Hi All,
>> >
>> > I'm not mantainer at all, but I've being using UKSM for a long time and remember
>> > to port it to 3.16 family once.
>> > UKSM seems good and stable and, at least for me, doesn't raised any errors.
>> > AFAIK the only limitation I know (maybe I has been fixed already) it isn't able
>> > to work together with zram stuff due to some race-conditions.
>> >
>> > Cheers,
>> >
>> > Marco A Benatto
>> > Mandriva OEM Developer
>> >
>>
>> http://kerneldedup.org/forum/forum.php?mod=viewthread&tid=106
>> As i did find, uksm not conflicting with zram (or zswap - on my system).
>
> Interesting,
>
> I've contacted the mantainers to send some patches in April and they said me this:
>
> "The biggest problem between UKSM/KSM and zswap is that pages can be reclaimed so
> fast by zswap before UKSM/KSM can have a chance to merge those can be merged.
>
> So one of the ideas that make a direct solution is that:
> 1. sleep the processes who trigger the zswap
> 2. wake up the UKSM thread and adjust the scan parameters properly to make it
> sample the whole memory in a limited time to judge if there are any VMAs need to
> be worked on.
> 3. If there are those VMAs then merge them at full speed. if there not,
> sleep UKSM.
> 4. Wake up the zswap code pathes and judge that if memory is enough to satisfy
> the requests. If there is enough memory then return and redo the memory
> allocation.
> 5. if there is not, then go on to do zswapping.
>
> This is just an outline of ONE of the solutions. It need to be carefully
> tweaked. Direct page reclaiming of zswap is a time sensitive code path
> , we cannot add too much overhead by doing this,
> otherwise it loses its meaning."
>
>> ---
>> Offtop:
>> Why i open up question about UKSM?
>>
>> May be we (as community, who want to help) can split out UKSM in
>> "several patches" in independent git repo. For allowing maintainers to
>> review this.
>>
>> Is it morally correct?
>>
>> UKSM code licensed under GPL and as i think we can feel free for port
>> and adopt code (with indicating the author)
>>
>> Please, fix me if i mistake or miss something.
>> This is just stream of my thoughts %_%
>> ---
>
> If there's no problem on that and if you don't mind, I can help you on this.
> What dou you think?

So cool, lets do it =3
https://github.com/Nefelim4ag/linux-uksm I've created a temporary
git-repository.
I am trying to split one big patch into several independent patches.
Patch is attached to e-mail.

Perhaps we can move conversation to personal emails(for you - to working)?

> Cheers,
>
> Marco A Benatto
> Mandriva OEM Developer

-- 
Have a nice day,
Timofey.

View attachment "0002-uksm-0.1.2.3-for-linux-next-20141016.ge.1.patch" of type "text/x-patch" (178578 bytes)