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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68C6BC61DA4 for ; Sun, 5 Mar 2023 20:42:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229699AbjCEUkK (ORCPT ); Sun, 5 Mar 2023 15:40:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41746 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229500AbjCEUkI (ORCPT ); Sun, 5 Mar 2023 15:40:08 -0500 Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com [66.111.4.27]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB03611EA6 for ; Sun, 5 Mar 2023 12:40:06 -0800 (PST) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id 46AC75C0046; Sun, 5 Mar 2023 15:40:05 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute1.internal (MEProxy); Sun, 05 Mar 2023 15:40:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= invisiblethingslab.com; h=cc:cc:content-type:content-type:date :date:from:from:in-reply-to:message-id:mime-version:reply-to :reply-to:sender:subject:subject:to:to; s=fm1; t=1678048805; x= 1678135205; bh=wC95Fc8WLi0uoy3J/mMJTNPyh7Buzl1RCLVdf0LxT/8=; b=D tJfEicQN85wYIe4pDF0QhlBpKUWIrjnnU1Odjx/jcH0q2aXlfmP/o1Me7ukqjIR0 O4x+N3YkKOaW0IUPS5VJsD3Xx9M2eOHE222nyuXAuLu0ElVj93Cnq8j7Cs0NEBxV ETQqCOBVnyoGfsfyibdaGRbHy/KqpZRuqLtJ8fX+RiQtgpyXo9a9io+hHJDmp3YE xpzlZOB5gBhk71W18mIQ7is/4caaYIfGFjGtI4zGD7/swo+d+dgUNYgrfUP7T6wv PmthfBMj/oFnTJq4p9g10+i5Ju3aJBnM57F0ZO7gCZnRTOmIN0y9O7iudB5rNcsQ fmmZsnslf6QRqekuM2s1w== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:message-id :mime-version:reply-to:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; t=1678048805; x=1678135205; bh=wC95Fc8WLi0uoy3J/mMJTNPyh7Bu zl1RCLVdf0LxT/8=; b=JAScaSZf6HoDj1K54NYs0XsJXBis+6iCdT9z9PN7RDWs m6iC8hxpWCY7hv5RR/0hkSufyha98z++NuUdgXS2hfIFpH7QtGif3myg9YKhqttC vFiWzoU9985MN0Gyk3LlvADij1mZwmahhR2pF/aX3AWvxkKBd8PcCHS5TNi7kBEh rPbtPykImPbT+pUTZWgcLqpq3Qz8oFROO2lGPEz2dBcWV4mP9Q/xkMu2+3fhrb5C m0feXXJsRNXtshY1GyN5Q85pE73TF+nVz7wCBvr7/fKMt2efuNxSjTT/bO3aWNlf JLbsJ6KzM29GJgB0wdk4XMjUhWjE4x5b+Vg9DAvsSw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrvddtgedgudeflecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpeffhffvvefukfhrgggtsehttdertddttddvnecuhfhrohhmpeffvghmihcu ofgrrhhivgcuqfgsvghnohhurhcuoeguvghmihesihhnvhhishhisghlvghthhhinhhgsh hlrggsrdgtohhmqeenucggtffrrghtthgvrhhnpefhleetjeefvdegieevjedtteduieel feeileejleeuhfehleegudduleefuefhjeenucevlhhushhtvghrufhiiigvpedtnecurf grrhgrmhepmhgrihhlfhhrohhmpeguvghmihesihhnvhhishhisghlvghthhhinhhgshhl rggsrdgtohhm X-ME-Proxy: Feedback-ID: iac594737:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 5 Mar 2023 15:40:04 -0500 (EST) Date: Sun, 5 Mar 2023 15:40:02 -0500 From: Demi Marie Obenour To: Joe Thornber Cc: "development, device-mapper" , Linux Kernel Mailing List , Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= , Qubes OS Development Mailing List , dm-devel@lists.ewheeler.net Subject: Thin pool CoW latency Message-ID: Reply-To: CAJ0trDYAyHHh2crMAQuQPMt3FzFmii0nmLnsL5N-cdhfvWZnMg@mail.gmail.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; x-action=pgp-signed Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Like Eric, I am very concerned about CoW latency and throughput. I am almost certain that allocating new blocks and snapshot copy-on-write are _the_ hot paths in Qubes OS. In particular, I suspect that workloads such as building an image in a throwaway VM or installing packages onto a root volume that had just been shapshotted are dominated by metadata operations, rather than by in-place updates. I suspect that frequently-snapshotted volumes will observe similar behavior in general. - -- Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEdodNnxM2uiJZBxxxsoi1X/+cIsEFAmQE/iEACgkQsoi1X/+c IsHLFxAAyWT4SlSueR15VxrwG07T9cEl7vnQwKHKWdzFBoWl0KhvyjLr52t0ip1J HPmwTVaor+53E+0bLUlgqA7G56a6PwxWWAQ6CsHHdxQ1xo3Serigkhys2hmwRq+e WPVrDSVRQLzOj/Qg6MsF2PPzdL5aNjK2QeHnWVcyXvfwZDhDCJKzz2iJC/ENjFNW X2bD3wazu6A+aFsxjLHtf5wAa0+PhppcEhUZNSgQiC9SiT5DPFabLIIi7jgb0Nlg v5GciAp1w0J+SUq2Wh4atrPR11Sj878AnJ872/Ku+pLseVu8h7N/60p8OwBm47Ak GNZlgq7XF1lien/3eFq9mfJKGc97MxveEkiqI46ankVs+bDQOlUbXriMlINEeT8r AzCar8pYx5W/xFb/gvYPnksATlOxLAaQ1jPZ1j0dIRaPtoOngtQ64TC5alRirGCK uqQ7c1Soj7D3SjahrbQkoqcyODmRoC/55Pu8Klb2l96S91rSRtvca+EV05GNXmyN eaArdGNuWPmzq6E8mQj3YrYnn18Z/x3WRr77xGVTAjUCGDPCE01+o/0G9P/+4cpv olMs1/ludL/WzbBe9scp2JK442dGwE/pcBiWI34DmxbLZTb1baG4BEX6mbDdfnpk SmIQv1RcHtbf16nvuhg+QVXnjAL5qQNiGVWxF9PTH8799wmcsdM= =/KY9 -----END PGP SIGNATURE-----