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 2251EE77198 for ; Mon, 6 Jan 2025 14:53:51 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1QBb1SxSbkhq0fjJPP/D8igQzmWEtDwWTFQrDDQ04OM=; b=PSU+FiJrbAnmzxwf6uQwaOlQLc 1MYWiXvRqXw3tj5uZpTYAGqrizQ+c9vH44l3S4L1wrFUDFy7eRS1VJ8TzxCHO6G6KWSMfgyoUeScf aJiUw1CrSkZD8wFz9cRo0eBtHrRKdFPV2uNu2ZbkVNyKvsv/W/kGF34bdzKaW7O29fbsv7DgUkWeu XSMe5cER+iC8m3/6cWmmYyVmFoHXPOAbMHdJfbiJNm2zWjqEEcQwtDgzTBNR02Wv+heDY15uWjctD OIeegm/g/eifBvS7jTqWdb5jQTC+iLJV/ebtbRoiFJOUpFGFNdbSspoolf40Aw2XnRvk7nonHKOEQ ejrLX4zg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tUoUF-00000001frP-2cr3; Mon, 06 Jan 2025 14:53:47 +0000 Received: from out-170.mta1.migadu.com ([2001:41d0:203:375::aa]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tUoGc-00000001bmX-0NBI for linux-nvme@lists.infradead.org; Mon, 06 Jan 2025 14:39:43 +0000 Message-ID: <6c63dd3a-378d-471f-8af0-725edc3785ed@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1736174377; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1QBb1SxSbkhq0fjJPP/D8igQzmWEtDwWTFQrDDQ04OM=; b=JLi2So6YMgc1dnvVKl8hkq5wxmbpmbt93tP9dW3JvqKloiWUhxBzIW4jWw3BIH4IdoUiuD 9wXf2ugoGGIVDR78uxu6XWy1ZOr8e/zHj8vPORYlyin6Oy6bcJETw/dBqjDwmgeLJYnrPl dmUulL7tkr6kcGySvUEWJOd+D5/Ekcs= Date: Mon, 6 Jan 2025 15:39:34 +0100 MIME-Version: 1.0 Subject: Re: [LSF/MM/BPF TOPIC] Improving Block Layer Tracepoints for Next-Generation Backup Systems To: Christoph Hellwig , Vishnu ks Cc: Song Liu , lsf-pc@lists.linux-foundation.org, linux-block@vger.kernel.org, bpf@vger.kernel.org, linux-nvme@lists.infradead.org References: Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Zhu Yanjun In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250106_063942_406864_4B1D6AC6 X-CRM114-Status: GOOD ( 12.90 ) 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 06.01.25 08:37, Christoph Hellwig wrote: > 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. If I get you correctly, you mean, the action that **drivers often change the sector during submission processing** will generate a lot of tracepoint events. Thus, this will make difference on the performance of the whole system. If yes, can we only monitor fentry/fexit of some_important_key_function to reduce the eBPF events? Thus this will not generate too many events then make difference on the performance. Zhu Yanjun > >> 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.