linux-kernel - Re: [RFC][PATCH v2 2/3] zram: use zs_get_huge_class_size

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Message-ID: <20160222020547.GC488@swordfish>
Date:	Mon, 22 Feb 2016 11:05:47 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Minchan Kim <minchan@...nel.org>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joonsoo Kim <js1304@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH v2 2/3] zram: use zs_get_huge_class_size_watermark()

On (02/22/16 10:59), Sergey Senozhatsky wrote:
[..]
> > > > Having said that, I agree your claim that uncompressible pages
> > > > are pain. I want to handle the problem as multiple-swap apparoach.
> > > 
> > > zram is not just for swapping. as simple as that.
> > 
> > Yes, I mean if we have backing storage, we could mitigate the problem
> > like the mentioned approach. Otherwise, we should solve it in allocator
> > itself and you suggested the idea and I commented first step.
> > What's the problem, now?
> 
> well, I didn't say I have problems.
> so you want a backing device that will keep only 'bad compression'
> objects and use zsmalloc to keep there only 'good compression' objects?
> IOW, no huge classes in zsmalloc at all?

hm, in the worst case we can have _for example_ 80+% of writes to be 'bad
compression'. that turns zsmalloc into a 3rd wheel, and makes it almost
unneeded. hm, may be it's better for now to fix zsmalloc-zram pair.

	-ss