From mboxrd@z Thu Jan 1 00:00:00 1970 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.subspace.kernel.org (Postfix) with ESMTPS id AF765184F; Mon, 6 Jan 2025 07:37:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736149052; cv=none; b=myf+mT5OO/xow61HadbwxM9DUnK1d4Lpwxc4TuBMcTHHD5N63m6FWBeLsLzPRSWHenj8lXFDJ9XKfTCOb46yk2eQvLceNOC1cFjslqxmbkd186HnjhDD4bVoDXRkjgrRWcI3tQfO9Wi4Embig/V7bHqxlE3WdFwPx2vHWy+wHPE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736149052; c=relaxed/simple; bh=Tyumh1CB+btpYXVfR9YsyTiQzEBfoBoQ0Hl+mVnpDqc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rSt4sR4RLKcGTqrqYGYlP5ap3hHOsymOgSdETfsaM6lC6KNow2MmguuEu4DkGiC+BpYx+nh1zXuEkKWVRxUJwnuxabDeKXN4TA9wx4FtXzucPV+2IPZvO+A074XUCr1ZkYXHuiI/aJmVVsQa02v2vQ70OKuFkChalDmDyRGHzuQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=VQWLAz2u; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="VQWLAz2u" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=JrYxbYSuhWPmWtfO+OtFAYtumYZrpI/Z+uaU0zNmXPA=; b=VQWLAz2uoZtqQvVkvA//o23JD5 xaa8QRQC+d3sIhdEI3UY8U2KHGFmURkK8QMc6NEQnatRSYnDFl1cm8fEvNBbCRmg/+UufnYl6aZp/ OzOYsdIS9h98A2wikJxu+6r+BHlgw0YG6efH5NSvRXMpXXIETLUcenq7bh/gvMQiDcEUFL0nIEwsn AJGt9ua1GKl/z/RuDYqzhJLoAE2TOR0tPmdh/7LsNQM9mZN/9hEVQ2cRyPzJADZRhYan1vPgnIP2x Uu862/Yj4Xx/S6efU6dY5w9vm+8AdU6qOmbqY2VpFCN+V+CpWuBlbqOfTbMPoU2XmUIYAdfXC1GXz QpmMfllQ==; 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: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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.