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Wed, 02 Nov 2022 13:07:24 -0700 (PDT) Date: Wed, 2 Nov 2022 13:07:22 -0700 From: Minchan Kim To: Sergey Senozhatsky Cc: Andrew Morton , Nitin Gupta , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv4 0/9] zram: Support multiple compression streams Message-ID: References: <20221018045533.2396670-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221018045533.2396670-1-senozhatsky@chromium.org> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667419646; a=rsa-sha256; cv=none; b=in9HwcsdhVINY/rQhzXhLMlgHIT5fdvJ/8i9yXH/4uWoUsLJty54ZP5u+lLsBmrPEyPZHZ HlBF3ijF5Sb4gFk+K4aUikfcrAsKae+xVSCOq+bv0nfU7ogTcg3OnmABgzF6Z76lKSOTcw T2f8kwVaQiSTKVs0jLEECRWHhtyL9nE= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=QVTusBD2; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=pass (imf13.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.216.51 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667419646; 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=moK7+sMOMULoftfZaVBsMzmR/Xim4ClEpYiki4yAnI4=; b=Ge/Z+ANl6sLimS4qX5MNLTZM4AnxfD9tTU3VFNsWoac8Bj1m8j2Vaov0y2mpYdjak39GBE zH2PP71D9ASDhppc5Vv05vCoOTI+E5aqzUSkwvj2Q1ll6UXQ2omncYCILkHUvwWW+EKXsa Hoie6B2qzd/9hl+rJ5GSWVxlzIjC0cI= X-Stat-Signature: 4zhd1wu8u4s7n7kuqdjy96kmuo31j1fs X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 3A45320007 X-Rspam-User: Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=QVTusBD2; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=pass (imf13.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.216.51 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com X-HE-Tag: 1667419645-30218 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 Tue, Oct 18, 2022 at 01:55:24PM +0900, Sergey Senozhatsky wrote: > Hello, > > This series adds support for multiple (per-CPU) > compression streams (at point only 2). The main idea is that > different compression algorithms have different characteristics > and zram may benefit when it uses a combination of algorithms: > a default algorithm that is faster but have lower compression > rate and a secondary algorithm that can use higher compression > rate at a price of slower compression/decompression. > > There are several use-case for this functionality: > > - huge pages re-compression: zstd or deflate can successfully > compress huge pages (~50% of huge pages on my synthetic ChromeOS > tests), IOW pages that lzo was not able to compress. > > - idle pages re-compression: idle/cold pages sit in the memory > and we may reduce zsmalloc memory usage if we recompress those > idle pages. > > User-space has a number of ways to control the behavior > and impact of zram recompression: what type of pages should be > recompressed, size watermarks, etc. Please refer to documentation > patch. Hi Sergey, First of all, I am really sorry to attend the party too late. I absolutely agree the feature is really useful and even I am thinking to support multiple comression trials on the fly for future. So I'd like to introduce the feature more general shape to be extended later so review will go. Thanks!