From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EC38FE77188 for ; Mon, 6 Jan 2025 07:37:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=JrYxbYSuhWPmWtfO+OtFAYtumYZrpI/Z+uaU0zNmXPA=; b=J3GdSm3iBeMAlR7LObefUgsD2p dEFcAWLWl/nWcYMrEV06aXnT1G3vLEYKA4DE1+9Y4E4+qO2UZ024cEQSb9Tg+fACrSx7gs9rKq25c 2naOl4MHEikae8UsoEyNsc/G0xfobgtTkM5un+TENrD0p0jvT9gDR5gxdc9PKxsqadzEjq16LzZHJ KFgFR46hWAzt7Ea9RUMjFbSyFlQzwaHQgg473HeQ+x2css74k+8qkLMQDTCEAlikKfPkYbPC1NlSC MeMcjN24J72T2lMZ+07mGyLjsvAeCIk0lYlYRS9/KDmi01xbwJODKju8InXoG1d6vPBAP08lkGWar NKZBytuA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tUhgR-00000000QFO-0diD; Mon, 06 Jan 2025 07:37:55 +0000 Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tUhg0-00000000QBN-47yr; Mon, 06 Jan 2025 07:37:29 +0000 Date: Sun, 5 Jan 2025 23:37:28 -0800 From: Christoph Hellwig To: Vishnu ks Cc: Song Liu , hch@infradead.org, yanjun.zhu@linux.dev, lsf-pc@lists.linux-foundation.org, linux-block@vger.kernel.org, bpf@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: [LSF/MM/BPF TOPIC] Improving Block Layer Tracepoints for Next-Generation Backup Systems Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Sat, Jan 04, 2025 at 11:22:40PM +0530, Vishnu ks wrote: > 1. Uses eBPF to monitor block_rq_complete tracepoint to track modified sectors You can't. Drivers can and often do change the sector during submission processing. > 2. Captures sector numbers (not data) of changed blocks in real-time > 3. Periodically syncs the actual data from these sectors based on > configurable RPO > 4. Layers these incremental changes on top of base snapshots And all of that is broken. If you are interested in this kind of mechanism help upstreaming the blk-filter work, which has been explicitly designed to support that. Before that you should really undestand how block devices and file systems work, as the rest of the mail suggested a very dangerous misunderstanding of the basic principles.