From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f175.google.com ([209.85.223.175]:34212 "EHLO mail-io0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752547AbbIPPUM (ORCPT ); Wed, 16 Sep 2015 11:20:12 -0400 Received: by iofb144 with SMTP id b144so234429123iof.1 for ; Wed, 16 Sep 2015 08:20:12 -0700 (PDT) Received: from [127.0.0.1] (rrcs-70-62-41-24.central.biz.rr.com. [70.62.41.24]) by smtp.googlemail.com with ESMTPSA id n14sm10557211ioi.15.2015.09.16.08.20.10 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Sep 2015 08:20:10 -0700 (PDT) Subject: Re: FYIO: A rant about btrfs To: linux-btrfs@vger.kernel.org References: <20150916144355.GA1285@invalid> From: Austin S Hemmelgarn Message-ID: <55F988A6.8070109@gmail.com> Date: Wed, 16 Sep 2015 11:20:06 -0400 MIME-Version: 1.0 In-Reply-To: <20150916144355.GA1285@invalid> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms030107090405080000020709" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms030107090405080000020709 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-09-16 10:43, M G Berberich wrote: > Hello, > > just for information. I stumbled about a rant about btrfs-performance: > > http://blog.pgaddict.com/posts/friends-dont-let-friends-use-btrfs-for= -oltp > > MfG > bmg > It is worth noting a few things that were done incorrectly in this testin= g: 1. _NEVER_ turn off write barriers (nobarrier mount option), doing so=20 subtly breaks the data integrity guarantees of _ALL_ filesystems, but=20 especially so on COW filesystems like BTRFS. With this off, you will=20 have a much higher chance that a power loss will cause data loss. It=20 shouldn't be turned off unless you are also turning off write-caching in = the hardware or know for certain that no write-reordering is done by the = hardware (and almost all modern hardware does write-reordering for=20 performance reasons). 2. He provides no comparison of any other filesystem with TRIM support=20 turned on (it is very likely that all filesystems will demonstrate such=20 performance drops. Based on that graph, it looks like the device=20 doesn't support asynchronous trim commands). 3. He's testing it for a workload is a known and documented problem for=20 BTRFS, and claiming that that means that it isn't worth considering as a = general usage filesystem. Most people don't run RDBMS servers on their=20 systems, and as such, such a workload is not worth considering for most=20 people. His points about the degree of performance jitter are valid however, as=20 are the complaints of apparent CPU intensive stalls in the BTRFS code,=20 and I occasionally see both on my own systems. --------------ms030107090405080000020709 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgMFADCABgkqhkiG9w0BBwEAAKCC Brgwgga0MIIEnKADAgECAgMQblUwDQYJKoZIhvcNAQENBQAweTEQMA4GA1UEChMHUm9vdCBD QTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNp Z25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcwHhcN MTUwMzI1MTkzNDM4WhcNMTUwOTIxMTkzNDM4WjBjMRgwFgYDVQQDEw9DQWNlcnQgV29UIFVz ZXIxIzAhBgkqhkiG9w0BCQEWFGFoZmVycm9pbjdAZ21haWwuY29tMSIwIAYJKoZIhvcNAQkB FhNhaGVtbWVsZ0BvaGlvZ3QuY29tMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEA nQ/81tq0QBQi5w316VsVNfjg6kVVIMx760TuwA1MUaNQgQ3NyUl+UyFtjhpkNwwChjgAqfGd LIMTHAdObcwGfzO5uI2o1a8MHVQna8FRsU3QGouysIOGQlX8jFYXMKPEdnlt0GoQcd+BtESr pivbGWUEkPs1CwM6WOrs+09bAJP3qzKIr0VxervFrzrC5Dg9Rf18r9WXHElBuWHg4GYHNJ2V Ab8iKc10h44FnqxZK8RDN8ts/xX93i9bIBmHnFfyNRfiOUtNVeynJbf6kVtdHP+CRBkXCNRZ qyQT7gbTGD24P92PS2UTmDfplSBcWcTn65o3xWfesbf02jF6PL3BCrVnDRI4RgYxG3zFBJuG qvMoEODLhHKSXPAyQhwZINigZNdw5G1NqjXqUw+lIqdQvoPijK9J3eijiakh9u2bjWOMaleI SMRR6XsdM2O5qun1dqOrCgRkM0XSNtBQ2JjY7CycIx+qifJWsRaYWZz0aQU4ZrtAI7gVhO9h pyNaAGjvm7PdjEBiXq57e4QcgpwzvNlv8pG1c/hnt0msfDWNJtl3b6elhQ2Pz4w/QnWifZ8E BrFEmjeeJa2dqjE3giPVWrsH+lOvQQONsYJOuVb8b0zao4vrWeGmW2q2e3pdv0Axzm/60cJQ haZUv8+JdX9ZzqxOm5w5eUQSclt84u+D+hsCAwEAAaOCAVkwggFVMAwGA1UdEwEB/wQCMAAw VgYJYIZIAYb4QgENBEkWR1RvIGdldCB5b3VyIG93biBjZXJ0aWZpY2F0ZSBmb3IgRlJFRSBo ZWFkIG92ZXIgdG8gaHR0cDovL3d3dy5DQWNlcnQub3JnMA4GA1UdDwEB/wQEAwIDqDBABgNV HSUEOTA3BggrBgEFBQcDBAYIKwYBBQUHAwIGCisGAQQBgjcKAwQGCisGAQQBgjcKAwMGCWCG SAGG+EIEATAyBggrBgEFBQcBAQQmMCQwIgYIKwYBBQUHMAGGFmh0dHA6Ly9vY3NwLmNhY2Vy dC5vcmcwMQYDVR0fBCowKDAmoCSgIoYgaHR0cDovL2NybC5jYWNlcnQub3JnL3Jldm9rZS5j cmwwNAYDVR0RBC0wK4EUYWhmZXJyb2luN0BnbWFpbC5jb22BE2FoZW1tZWxnQG9oaW9ndC5j b20wDQYJKoZIhvcNAQENBQADggIBABr5e8W+NiTER+Q/7wiA2LxWN3UdhT3eZJjqqSlP370P KL5iWqeTfxQ67Ai/mHbJcT2PgAJ+/D2Ji+aRR03UWnU/vtOwzyDLUMstqnfl0Zs+sz/CJe7x nBA5jlpjC2DKuMVfbPze7eySaen7XSGFHKE1QoVIIpQ2kVjC4nbbJQnUbAVX1Iz29WxeVGt9 XYigz3tDPf3tglN+q23E7YjQl4abTIoM7i98yV1H9gfY8lFfKZ6jREB9+n6ie2EwS3Kat2mG tl2wBx4MfRnoSQSKsLKQ5oTwhWf0JqlFwpLfl374p0Njcykej9/jnWG8Ks1V/AXTHqI4eyIP Mf5yMZkPv7n7LS9WWKdG4Nd38iv4T2EiAaWsmgu+r81qL5CJu9AyA0SBS4ttKf6k3e63w2Mv N9R45vpQ3QhAhfWyFxFhZN95APe3YECDG3+XIRJpRYPEtHuIsOyzI70ajF93gg/BidvqKsmV MM2ccktDMfqwZXea6zey7F8Geu9R7BqjXmG2HlNuXu7e/xnHOgXf5D3wPmnRLlBhXL1Ch97a w2KjaupjpAHfFjv5kGnZXN87UvvlwzIZiKXwa3vTDwK+rrKn/sHPkfDZPSiyt/ZBIK6lX83P 34H/CzGg+Kx57rHYOIHGumIvpDa5vfWp8O0sGgawb1C2Aae4sTUVIWmIjVuGI062MYIE0TCC BM0CAQEwgYAweTEQMA4GA1UEChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNl cnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcN AQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxBuVTANBglghkgBZQMEAgMFAKCCAiEwGAYJKoZI hvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTUwOTE2MTUyMDA2WjBPBgkq hkiG9w0BCQQxQgRA+UaC3UtgeqTU76DRUz+D2RI6scbEhIeIC/mzBLLaj70xUiqcNzw/d7Og hNT3fkdQxDzH0vyQ4md4y5pqcxJqXjBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIGRBgkrBgEEAYI3EAQxgYMwgYAweTEQMA4GA1UE ChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlD QSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy dC5vcmcCAxBuVTCBkwYLKoZIhvcNAQkQAgsxgYOggYAweTEQMA4GA1UEChMHUm9vdCBDQTEe MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25p bmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxBuVTAN BgkqhkiG9w0BAQEFAASCAgBarBgAba4F0+0/3XGm+t/NKiqsHxecnm4z6KDLlyoDRzMAOxOC 708sZSrPSpR2sJz894KoQ/U8goh6yT1WQ/yzXUxf0PqMnTitrskgCOe/kYgF20aEiu3R8+MV 6D5BsYtW7F9LtECuRcb6SeKOP5585ZeRzULR4fEIR+h9U/QHFaN9fwFU3UhmgEo2pLn9dV39 Zw5NJr6EkDNwqB7urCfGtglA9X4CUNN/jDNNwDsP/YjH8e/llFr4ya5HNJC4G122qw7r+ngm X8jswlZ8+mOq1WIlX8WpCSEQ5p5vNyE3iRrKlMshs6VOziPaldYIZ8HN/sIUVhu4QxEm4yA2 l+LlgttXg3JIAlbtW4Uelw0p2QSewUIY6fQFs3sINrlKHzztPOK1HbZPD5Zo1zyUe2YfeAVH cCKttlkuoCArtGAz5Pq16SBD1PJhX6cmfdAprEqvsUqR8MhEAvBdFqhcEZ96cqwAF+qvelZu CS3CKXyKWd/cjDa8RcUGjGI4DruMvsKKdRFsmLsICP2HIEOiEDKgNtjsBHpRrnoitOEmmdmq oYKPOPhmcIr6lLUEcGu15tl/8oFch3wMIMZd/uLdctb2XH3+XLGF0ujTh3w22+ABn77zmXUm +Rhi4igaHGER8w1LQnrYRbgCIxTGbSfJQ4sfLluYYrK7KWNo1f2thwFlygAAAAAAAA== --------------ms030107090405080000020709--