From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f181.google.com ([209.85.223.181]:36853 "EHLO mail-io0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752392AbbIPTVd (ORCPT ); Wed, 16 Sep 2015 15:21:33 -0400 Received: by ioii196 with SMTP id i196so240418042ioi.3 for ; Wed, 16 Sep 2015 12:21:32 -0700 (PDT) Subject: Re: FYIO: A rant about btrfs To: Martin Tippmann References: <20150916144355.GA1285@invalid> <55F988A6.8070109@gmail.com> Cc: linux-btrfs@vger.kernel.org From: Austin S Hemmelgarn Message-ID: <55F9C136.3080800@gmail.com> Date: Wed, 16 Sep 2015 15:21:26 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms080004020807080104080500" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms080004020807080104080500 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-09-16 12:45, Martin Tippmann wrote: > Hi, > > 2015-09-16 17:20 GMT+02:00 Austin S Hemmelgarn : > [...] >> 3. He's testing it for a workload is a known and documented problem fo= r >> 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 thei= r >> systems, and as such, such a workload is not worth considering for mos= t >> people. >> >> His points about the degree of performance jitter are valid however, a= s are >> the complaints of apparent CPU intensive stalls in the BTRFS code, and= I >> occasionally see both on my own systems. > > Are there any conceptual or design properties that make btrfs perform > worse in this workload compared to ZFS or F2FS that both do CoW and > share some similarity? ZFS has been around for much longer, it's been mature and feature=20 complete for more than a decade, and has had a long time to improve=20 performance wise. It is important to note though, that on low-end=20 hardware, BTRFS can (and often does in my experience) perform better=20 than ZFS, because ZFS is a serious resource hog (I have yet to see a=20 stable ZFS deployment with less than 16G of RAM, even with all the fancy = features turned off). As for F2FS, it was designed from the ground up for high performance and = efficiency. BTRFS started (from what I understand) as more of an=20 experiment, and as such the original code was not particularly optimized.= > > If not then I still think (from a user perspective) it it still > interesting too look where the difference is coming from? There is > also a quite old talk with some unfortunate numbers for btrfs from the > XFS developer Dave Chinner: > https://www.youtube.com/watch?v=3DFegjLbCnoBw - is this already > resolved? 2012 is 3 years ago. That depends on what you mean by resolved. In every test I've done that = wasn't a specialized benchmark designed to simulate a particular=20 workload, I've gotten roughly equal performance between XFS and BTRFS=20 (YMMV of course, especially because my usecase is not very typical of=20 most people (primarily building software and running BOINC projects)).=20 I use BTRFS mostly because it makes online reprovisioning much easier=20 (you can't migrate an XFS filesystem to a new block device online, and=20 you also can't shrink one). It's also worth noting that Dave Chinner usually comes forth with=20 numbers extolling the value of XFS when a new filesystem gets proposed.=20 In my experience, for small scale usage, ext* gets better performance=20 than almost anything else, including XFS. > > From reading the list I understand that btrfs is still very much work > in progress and performance is not a top priority at this stage but I > don't see why it shouldn't perform at least equally good as ZFS/F2FS > on the same workloads. Is looking at performance problems on the > development roadmap? Performance is on the roadmap, but the roadmap is notoriously=20 short-sighted when it comes to time-frame for completion of something.=20 You have to understand also that the focus in BTRFS has also been more=20 on data safety than performance, because that's the intended niche, and=20 the area most people look to ZFS for. --------------ms080004020807080104080500 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 hvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTUwOTE2MTkyMTI2WjBPBgkq hkiG9w0BCQQxQgRAlX/P/cGuejz7YrnJEv3/CgaQg5n+OPHU4+LwZzJWcNZGr19ukfWofqwI NcuFNvgU1seFCBu9pZkEIoTvmJffKjBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIGRBgkrBgEEAYI3EAQxgYMwgYAweTEQMA4GA1UE ChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlD QSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy dC5vcmcCAxBuVTCBkwYLKoZIhvcNAQkQAgsxgYOggYAweTEQMA4GA1UEChMHUm9vdCBDQTEe MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25p bmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxBuVTAN BgkqhkiG9w0BAQEFAASCAgCLozXZeezWlkq7kDHqL6/AV5FBqdpQ8z89SYILbB0PP2CCtCD9 LTVDtjD3jTurE7hmJiIO10Ef6eMylLCMuU4TyJbO9N5r0sZ015WNPoaAoVTLMmIhYLQ1CYiw Rp/b7Kt3jq7gIgiA9tYMcW10/JTpK2IJKvSnrafdJZuULDZ5RpHs9u1gCMje033BroGgdQYX Wp7aURkhcLV+ouBGxvaiBUpSTFGzhx1bkATg460f5IZl6BogJWZJ+3VGpwZK5HISsLX8LSpz oWYS5uPZK+fwOLDtaXTtGpPhVNuImcNjlC2t683aBVpCaCv1x4hEsZIynARO6UwXICbV/fLM k6qZsEAc/RrCx7tWmVjDkU6DswXf2MDiQ+KZIEHIjcTb7sZRszEK9mweAwCW7YqBtt2U6V38 mKPU9KshNQqm/6nPMPNWE+eHwV7XY7iAQQru8iiB5o9l0eNqBgQy/oK9RD5E6Mes9/sce8ZV a+OpSb5bzVGe/jdI0NgyLe2nXnPMAOeP0hYwiDU9bly2wW2LL2imqgthWrQ3WebTqglcAqbp ducLLOns1+XP7LZPecyyjoiKVzZ67P0O1VXQgxLGOcLUAOfnRYWwxgAi8YJ7TU4C+pT2LEfQ ZU9/nEkUcYqXHl22pR8RM2Hiqshoee5WIc7SFiWsSWEIm0qy8vgVIkCYogAAAAAAAA== --------------ms080004020807080104080500--