From: Minchan Kim <minchan@kernel.org>
To: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Nitin Gupta <ngupta@vflare.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCHv4 2/9] zram: Add recompression algorithm sysfs knob
Date: Thu, 3 Nov 2022 09:34:51 -0700 [thread overview]
Message-ID: <Y2Ptq1GZISCD7Mor@google.com> (raw)
In-Reply-To: <Y2Mv4l+V9iCv9EMg@google.com>
On Thu, Nov 03, 2022 at 12:05:06PM +0900, Sergey Senozhatsky wrote:
< snip >
> > Just open question(I might be too paranoid?)
> >
> > I am thinking someone want to add third comp algorithm in future
> > to balance decompression and memory efficiency.
> >
> > If it's not too crazy idea, let's think about the interface.
> > Maybe, could we make the recomp knobs works like list?
> >
> > # A primary comp
> > echo "A" > /zram/comp_algo
> >
> > # Multiple secondary comps
> > echo "B threshold" > /zram/add_recomp_algo
> > echo "C threshold" > /zram/add_recomp_algo
> > echo "D threshold" > /zram/add_recomp_algo
>
> What is the threshold here? My design approach is that ZRAM doesn't do
As your term, watermark but yeah, priority you suggested would be good
for me.
> recompression on its own, so no magic is happening automatically. It's
> the user-space that triggers recompression for selected pages when
> user-space thinks it's time to. This allows us to have various flexible
> policies and consider things that ZRAM is not even aware of: battery level,
> free memory, CPU load average, etc. E.g. no recompression when all CPUs
> are busy rendering video game, or when we are draining battery too fast,
> etc.
>
> > "cat /zram/recomp_algo" shows the list
> >
> > echo "C" > /zram/remove_recomp_algo
> > will remove the C algorithm in stack.
>
> What is the use case for removal of a secondary algorithm?
Without the interface, How can we modify the selection if admin want to
change the order of second algorithms?
>
> > My point is that we don't need to implement it atm but makes the
> > interface to open the possibility for future extension.
> >
> > What do you think?
>
> So, as far as I understand, we don't have reason to add remove_recomp_algo
> right now. And existing recomp_algo does not enforce any particular format,
> it can be extended. Right now we accept "$name" but can do something like
> "$name:$priority". The only thing that we probably need to do is rename
> recomp_algo to either add_recomp_algo or register_recomp_algo?
Yeah, I like the name and priority format.
Only question is how we could support algorithm selection change
under considering multiple secondary algorithms.
next prev parent reply other threads:[~2022-11-03 16:38 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-18 4:55 [PATCHv4 0/9] zram: Support multiple compression streams Sergey Senozhatsky
2022-10-18 4:55 ` [PATCHv4 1/9] zram: Preparation for multi-zcomp support Sergey Senozhatsky
2022-11-02 20:13 ` Minchan Kim
2022-11-03 2:40 ` Sergey Senozhatsky
2022-10-18 4:55 ` [PATCHv4 2/9] zram: Add recompression algorithm sysfs knob Sergey Senozhatsky
2022-11-02 20:15 ` Minchan Kim
2022-11-03 3:05 ` Sergey Senozhatsky
2022-11-03 3:54 ` Sergey Senozhatsky
2022-11-03 17:10 ` Minchan Kim
2022-11-03 4:09 ` Sergey Senozhatsky
2022-11-03 5:36 ` Sergey Senozhatsky
2022-11-03 17:11 ` Minchan Kim
2022-11-03 16:34 ` Minchan Kim [this message]
2022-11-04 3:18 ` Sergey Senozhatsky
2022-11-04 4:53 ` Sergey Senozhatsky
2022-11-04 17:43 ` Minchan Kim
2022-11-04 23:41 ` Sergey Senozhatsky
2022-11-05 0:00 ` Sergey Senozhatsky
2022-11-07 19:08 ` Minchan Kim
2022-11-08 0:40 ` Sergey Senozhatsky
2022-11-05 0:01 ` Minchan Kim
2022-11-05 1:30 ` Sergey Senozhatsky
2022-11-04 16:34 ` Minchan Kim
2022-11-04 23:25 ` Sergey Senozhatsky
2022-11-04 23:40 ` Minchan Kim
2022-11-04 23:44 ` Sergey Senozhatsky
2022-11-05 0:02 ` Minchan Kim
2022-10-18 4:55 ` [PATCHv4 3/9] zram: Factor out WB and non-WB zram read functions Sergey Senozhatsky
2022-11-02 20:20 ` Minchan Kim
2022-11-03 2:43 ` Sergey Senozhatsky
2022-10-18 4:55 ` [PATCHv4 4/9] zram: Introduce recompress sysfs knob Sergey Senozhatsky
2022-11-02 21:06 ` Minchan Kim
2022-11-03 3:25 ` Sergey Senozhatsky
2022-11-03 6:03 ` Sergey Senozhatsky
2022-11-03 17:00 ` Minchan Kim
2022-11-04 3:48 ` Sergey Senozhatsky
2022-11-04 7:12 ` Sergey Senozhatsky
2022-11-04 17:53 ` Minchan Kim
2022-11-04 17:27 ` Minchan Kim
2022-11-04 23:22 ` Sergey Senozhatsky
2022-11-04 7:53 ` Sergey Senozhatsky
2022-11-04 8:08 ` Sergey Senozhatsky
2022-11-04 17:47 ` Minchan Kim
2022-10-18 4:55 ` [PATCHv4 5/9] documentation: Add recompression documentation Sergey Senozhatsky
2022-10-18 4:55 ` [PATCHv4 6/9] zram: Add recompression algorithm choice to Kconfig Sergey Senozhatsky
2022-10-18 4:55 ` [PATCHv4 7/9] zram: Add recompress flag to read_block_state() Sergey Senozhatsky
2022-10-18 4:55 ` [PATCHv4 8/9] zram: Clarify writeback_store() comment Sergey Senozhatsky
2022-10-18 4:55 ` [PATCHv4 9/9] zram: Use IS_ERR_VALUE() to check for zs_malloc() errors Sergey Senozhatsky
2022-11-02 20:07 ` [PATCHv4 0/9] zram: Support multiple compression streams Minchan Kim
2022-11-03 3:36 ` Sergey Senozhatsky
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