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Fri, 04 Nov 2022 09:34:09 -0700 (PDT) Date: Fri, 4 Nov 2022 09:34:07 -0700 From: Minchan Kim To: Sergey Senozhatsky Cc: Andrew Morton , Nitin Gupta , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv4 2/9] zram: Add recompression algorithm sysfs knob Message-ID: References: <20221018045533.2396670-1-senozhatsky@chromium.org> <20221018045533.2396670-3-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667579651; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=65ZgVVpFNi6t9ZbbFlNcLrUCFgll39HRPUe2NP0G3ME=; b=Pdu+KY7Q4ctrPANHR/iZcfXth9xk1TIY6jc7oiZyIF7akD6aUEIAwNC+O++l9xr5X45C26 EWB46K6Q1KFWn98p657820BZBTSXy69OscdGFwrPt1FUxqGJrLs37avrqJKw7oFQ988Gpr A+rx2M7c0fMsWeeSqyquk04Z0pu19FA= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=Yn1Jq5Ry; spf=pass (imf11.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.216.51 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667579651; a=rsa-sha256; cv=none; b=ljPkotjFG5dH05xc2KDAKDSjhBqTsdIQ8BxbzXj2tipfs06b+LJvpY5AYQFKxWNkkkv2V5 /khEePZt3ArUiDxS09pGAFhQU4nN24fMiI84ITamOK1NR70Xw7xFFZhNqPlWt8kBHTNeLD DJv+ZkorkoICQcJ+7qG28RdDDoCy5eE= X-Stat-Signature: j8twkdknjn5o1nneq78dddopukhi9dxd X-Rspamd-Queue-Id: 7DB9040004 X-Rspamd-Server: rspam06 X-Rspam-User: Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=Yn1Jq5Ry; spf=pass (imf11.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.216.51 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) X-HE-Tag: 1667579651-880764 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Nov 04, 2022 at 12:18:43PM +0900, Sergey Senozhatsky wrote: > On (22/11/03 09:34), Minchan Kim wrote: > > > > 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. > > So what I was thinking about, and I'm still in the mental model that > re-compression is a user-space event, just like writeback, extension > of recompress sysfs knob with "algo_index" (or something similar) which > will mirror algorithm priority. > > Example: > > Configure 2 alternative algos, with priority 1 and 2 > > echo "name=lz4 priority=1" > recomp_algo > echo "name=lz5 priority=2" > recomp_algo > > Recompress pages using algo 1 and algo 2 > > echo "type=huge threshold=3000 algo_idx=1" > recompress > echo "type=idle threshold=2000 algo_idx=2" > recompress > > Maybe we can even pass algo name instead of idx. Let's use name rather than index.