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Wed, 02 Nov 2022 20:37:02 -0700 (PDT) Date: Thu, 3 Nov 2022 12:36:57 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , 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: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667446623; h=from:from: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=0VxL6xNBl5lCDUhZ3i3gS+DLrovMzwSN/smbDEMEamg=; b=AiUS1fp9Pg+IJzVpIHkmlFJrk1Cb7+P1ke832YGGiluQm2S0NNRIbVBeCmp054l347B+iS NXsLbd1qRPW8pH9ezju5Vj/GFOpV6ijfToOwv4ajOb0P849HrnuOpMPl02XL9kK5cJnyX3 USBe0/90pZJms0hQOyXJeAZKuNPUwQU= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=QMR1UHOQ; spf=pass (imf14.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.216.52 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667446623; a=rsa-sha256; cv=none; b=JYoZ+rnZHOgYVloigCf4C72SVb8nVrLd3Bbr9k8Gkm/NuMecSUO2tdsaNT4hvAHjSZwvQc FfKX+zRVA1nGf7y8V/7xsrjVEB4GwiA/FWWB5KC/T4JkpeQx4j1ROvr2Jze08OBBkZR4T9 vixLQMRauzHyKM9wqD4cvp9N+/+CdG0= Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=QMR1UHOQ; spf=pass (imf14.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.216.52 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Stat-Signature: kz4mxk1g1kki7y37pnk69t1aqhc7yxst X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 7EBB7100002 X-HE-Tag: 1667446623-104708 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000392, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Minchan, On (22/11/02 13:07), Minchan Kim wrote: [..] > 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. On the fly recompression (from the same context) was what I had as a first version (which was internal and was never published), and we didn't like it at all. It's too limited, has zero flexibility, zero extensibility and has too high of a price tag attached to it (in terms of CPU cycles, power and time). So we moved it to user-space (deferred context) and this unlocked numerous possibilities: recompress only when we really need to and, more importantly, can afford it; wire in numerous metrics: battery, CPU load etc. And many more.