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Sun, 05 Mar 2023 15:40:05 -0500 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 Message-ID: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Mailman-Approved-At: Mon, 06 Mar 2023 06:48:55 +0000 Subject: [dm-devel] Thin pool CoW latency X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: CAJ0trDYAyHHh2crMAQuQPMt3FzFmii0nmLnsL5N-cdhfvWZnMg@mail.gmail.com Cc: dm-devel@lists.ewheeler.net, "development, device-mapper" , Qubes OS Development Mailing List , Linux Kernel Mailing List , Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit -----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----- -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68C6BC61DA4 for ; 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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-----