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 X-Spam-Level: X-Spam-Status: No, score=-0.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A86E3C10F00 for ; Sat, 30 Mar 2019 13:09:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D08E218A6 for ; Sat, 30 Mar 2019 13:09:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="dAT58BW3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730835AbfC3NJb (ORCPT ); Sat, 30 Mar 2019 09:09:31 -0400 Received: from mout.gmx.net ([212.227.15.19]:37663 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730796AbfC3NJb (ORCPT ); Sat, 30 Mar 2019 09:09:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1553951368; bh=PJ6M9PECy3xrfF9UZYn6vO0LmA+rKlbAxvkMzBj8CgE=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=dAT58BW3Ky/+5C5luHaZ2Lxuw0dOZhmavLM53w8keqaNLSYU5dq7yjDae6/LR8OCV PaXXJiYxUPTDjPc+NzUt5abBhr+piJSMaWVNxrnbvtxaGga2RDnzrP2/mpaSSFM830 2UUTrGDF6avYTdxDaYC8tSvPaSI/kYKUmjztp00c= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([210.140.77.29]) by mail.gmx.com (mrgmx001 [212.227.17.184]) with ESMTPSA (Nemesis) id 0LrNl6-1gy9RR1ZtM-0134uz; Sat, 30 Mar 2019 14:09:27 +0100 Subject: Re: Is it possible that certain physical disk doesn't implement flush correctly? To: Supercilious Dude Cc: "linux-btrfs@vger.kernel.org" , Linux FS Devel , linux-block@vger.kernel.org References: <16edb2d0-ee41-908f-e0bf-5c27160ccff7@gmx.com> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0IlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT6JAVQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWCnQUJCWYC bgAKCRDCPZHzoSX+qAR8B/94VAsSNygx1C6dhb1u1Wp1Jr/lfO7QIOK/nf1PF0VpYjTQ2au8 ihf/RApTna31sVjBx3jzlmpy+lDoPdXwbI3Czx1PwDbdhAAjdRbvBmwM6cUWyqD+zjVm4RTG rFTPi3E7828YJ71Vpda2qghOYdnC45xCcjmHh8FwReLzsV2A6FtXsvd87bq6Iw2axOHVUax2 FGSbardMsHrya1dC2jF2R6n0uxaIc1bWGweYsq0LXvLcvjWH+zDgzYCUB0cfb+6Ib/ipSCYp 3i8BevMsTs62MOBmKz7til6Zdz0kkqDdSNOq8LgWGLOwUTqBh71+lqN2XBpTDu1eLZaNbxSI ilaVuQENBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAGJATwEGAEIACYWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWBrwIbDAUJA8JnAAAK CRDCPZHzoSX+qA3xB/4zS8zYh3Cbm3FllKz7+RKBw/ETBibFSKedQkbJzRlZhBc+XRwF61mi f0SXSdqKMbM1a98fEg8H5kV6GTo62BzvynVrf/FyT+zWbIVEuuZttMk2gWLIvbmWNyrQnzPl mnjK4AEvZGIt1pk+3+N/CMEfAZH5Aqnp0PaoytRZ/1vtMXNgMxlfNnb96giC3KMR6U0E+siA 4V7biIoyNoaN33t8m5FwEwd2FQDG9dAXWhG13zcm9gnk63BN3wyCQR+X5+jsfBaS4dvNzvQv h8Uq/YGjCoV1ofKYh3WKMY8avjq25nlrhzD/Nto9jHp8niwr21K//pXVA81R2qaXqGbql+zo Message-ID: <948a62d3-aa3e-418e-00df-d73d4dbfb5a6@gmx.com> Date: Sat, 30 Mar 2019 21:09:16 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nk8Hs40cmV9MR9zSgQnsOLP6JdZyKTUN7" X-Provags-ID: V03:K1:x417mq9hkfntfP2lZNWqEbuZCLOSkuKdsCez0HuzGrUTGSc7sOj aSYp1sKDkhZjoD9JwW+DN8Hxxsh4BUlyogTcAKhY0iXgsDOjSaWBakTRH08kw5Ykvbw9IXL L81/qNtja4ou+VKfBTxnVmuYNrdXJcNS2ooKSbtSrvYDglyYM6puouJmTJ6kt0vBtfP27x9 1eHN+MI1JLV9dYO7dAKag== X-UI-Out-Filterresults: notjunk:1;V03:K0:82aifa7zCl4=:g81eEFmatpV80rXq+4CcEr 7zTzbtVdc7kanH5GVZBtt1f7G3N6mZ5GRb9JXFO++fSMORg2ags3T1oqL3pcr+ZDejWTwVoZp P8p79XM52WpGTDUNnoVq6QRWxzWCk4kQIQTuBTO+RaHK8n44PN0fEW1fyg0rCryfWg6C2t4mD F7WrPzDZef7dxAsm4QtY8vBv2aqpD//Azni7B2mUH6vlILgNDxJhYg9AYmNEDrsSX0Wul0wwW lb/X7oJ05ZPj5mYd0fWXdPuNa0fJffU+WffnABxzskY5CoitEJnpYMLxmVrZXe8BnGu7ZPZ+s lWDgO8tMRxvfUy5QUPQlf4TsfvME9uM5OLyhNvd0nulk7vXaRZaXP4OoN2Q84uzmv/lTza1bq C0zdgVanPqR4kOdY2gkdgaz4m2HDFbcs8Mwuv1gSsQXnhqfPv6H38ZGAJmROs/vobMCqxOFIZ 04YsDv2LJ4L6wuchGckwJf9SVEnVs0V69x+id/PJDyHGo4Q4AhAAqM4DSD5s1ku22zGGqBuOw 98kzC9duJHWUNY9o0dL0AZWDd0NxssBhtFWejGeUTy5S2e/dVCGujztKGtC/NZTTmr6faXR53 vqfE0/ZKENVEg4lu7kBtoUlT48q6Yjkpu3Fj1pCEcZELXRBMZ+f44ySMOy3s1SArxWXoDfYhj XPZLIVCGabBFoEbTZVkerX5s4Gmg7huwZn3iqTZvj7xjhQvTGirzLI9ZQ1YbX5W68/gNR2rci 00RUAHNa4RIvZS3ar+raGfwDJWrKwgSo1XHRDPTgwD/fmm6wzVC6z4wNBVar86rgKaTUF5ngG +tu4fdlAqVZYaoNdl2yHJFPNO1W76pg4fleJjjrJsgW1uw86yRaJKrQOhiqoerZvYWL/8AsFp Vdy68OjN3P5VC0HELDXOaiuIc1zJ8LwQGShSPHpn31wtALBCFVQQ08D1BjAGfL Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --nk8Hs40cmV9MR9zSgQnsOLP6JdZyKTUN7 Content-Type: multipart/mixed; boundary="KgtofUoHmhYTUzhauCGGjTGnLMl2NU0B0"; protected-headers="v1" From: Qu Wenruo To: Supercilious Dude Cc: "linux-btrfs@vger.kernel.org" , Linux FS Devel , linux-block@vger.kernel.org Message-ID: <948a62d3-aa3e-418e-00df-d73d4dbfb5a6@gmx.com> Subject: Re: Is it possible that certain physical disk doesn't implement flush correctly? References: <16edb2d0-ee41-908f-e0bf-5c27160ccff7@gmx.com> In-Reply-To: --KgtofUoHmhYTUzhauCGGjTGnLMl2NU0B0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2019/3/30 =E4=B8=8B=E5=8D=889:04, Supercilious Dude wrote: > On Sat, 30 Mar 2019 at 13:00, Qu Wenruo wrote:= >> I'm purposing to measure the execution time of flush/fsync, not write.= >> >> And if flush takes 0ms, it means it doesn't really write cached data >> onto disk. >> >=20 > That is correct. The controller ignores your flush requests on the > virtual disk by design. When the data hits the controller it is > considered "stored" - the physical disk(s) storing the virtual disk is > an implementation detail. The performance characteristics of these > controllers are needed to make big arrays work in a useful manner. My > controller is connected to 4 HP 2600 enclosures with 12 drives each. > Waiting for a flush on a single disk before continuing work on the > remaining 47 disks would be catastrophic for performance. If controller is doing so, it must have its own power or at least finish flush when controller writes to its fast cache. For cache case, if we have enough data, we could still find some clue on the flush execution time. Despite that, for that enterprise level usage, it's OK. But for consumer level storage, I'm not sure, especially for HDDs, and maybe NVMe devices. So my question still stands here. Thanks, Qu >=20 > Regards >=20 --KgtofUoHmhYTUzhauCGGjTGnLMl2NU0B0-- --nk8Hs40cmV9MR9zSgQnsOLP6JdZyKTUN7 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlyfanwACgkQwj2R86El /qhhlAf7Bf5bAv8le3D2vLv3C6smPYhs2A78ef70Flt9oTPmIzyDn1OiLHLaxGMj q1/uOb923PO5cP4bOMKKQcFvCUE99QoNoWGmBCQIRLyhxBJOH3cCcrYhJGfywfzy Nx3GZwjX2ZORQo4DyJf6jWER/PfDgQX7JAhJVdN1kIYIwwTp78HwhN00KDI0xoet piUWc+H68Osl+HSrsqDi4vKVaok34ZKbet/VJg/nhxPG++8gTFBcUv7yTr3hiarj uuPBQd+utKZkUaQIqpqS2Yr/EjrD85+wv0dtDgFGCBhzW/a0BHdOSN5qEvH4tU1+ NYQAEUzaVE4jvx3FbpKJ0GdPfD47fg== =R7Og -----END PGP SIGNATURE----- --nk8Hs40cmV9MR9zSgQnsOLP6JdZyKTUN7--