Date: Thu, 20 Mar 2014 12:30:01 GMT From: Karl Denninger <karl@denninger.net> To: freebsd-fs@FreeBSD.org Subject: Re: kern/187594: [zfs] [patch] ZFS ARC behavior problem and fix Message-ID: <201403201230.s2KCU1vx057435@freefall.freebsd.org>
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The following reply was made to PR kern/187594; it has been noted by GNATS. From: Karl Denninger <karl@denninger.net> To: bug-followup@FreeBSD.org, karl@fs.denninger.net Cc: Subject: Re: kern/187594: [zfs] [patch] ZFS ARC behavior problem and fix Date: Thu, 20 Mar 2014 07:26:39 -0500 This is a cryptographically signed message in MIME format. --------------ms010203060907010901070002 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable I am increasingly-convinced with increasing runtime now on both=20 synthetic and real loads in production that the proper default value for = vfs.zfs.arc_freepages is vm.stats.vm.v_free_target less "just a bit." =20 Five percent appears to be ok for most workloads with RAM configurations = ranging from 4GB to the 24GB area (configurations that I can easily test = under both synthetic and real environments.) Larger invasions of the free target increasingly risk provocation of the = behavior that prompted me to get involved in working this part of the=20 code in the first place, including short-term (~5-10 second) "stalls"=20 during which the system appears to be locked up, but is not. It appears that the key to avoiding that behavior is to not allow the=20 ARC to continue to take RAM when a material invasion of that target=20 space has occurred. --=20 -- Karl karl@denninger.net --------------ms010203060907010901070002 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIFTzCC BUswggQzoAMCAQICAQgwDQYJKoZIhvcNAQEFBQAwgZ0xCzAJBgNVBAYTAlVTMRAwDgYDVQQI EwdGbG9yaWRhMRIwEAYDVQQHEwlOaWNldmlsbGUxGTAXBgNVBAoTEEN1ZGEgU3lzdGVtcyBM TEMxHDAaBgNVBAMTE0N1ZGEgU3lzdGVtcyBMTEMgQ0ExLzAtBgkqhkiG9w0BCQEWIGN1c3Rv bWVyLXNlcnZpY2VAY3VkYXN5c3RlbXMubmV0MB4XDTEzMDgyNDE5MDM0NFoXDTE4MDgyMzE5 MDM0NFowWzELMAkGA1UEBhMCVVMxEDAOBgNVBAgTB0Zsb3JpZGExFzAVBgNVBAMTDkthcmwg RGVubmluZ2VyMSEwHwYJKoZIhvcNAQkBFhJrYXJsQGRlbm5pbmdlci5uZXQwggIiMA0GCSqG SIb3DQEBAQUAA4ICDwAwggIKAoICAQC5n2KBrBmG22nVntVdvgKCB9UcnapNThrW1L+dq6th d9l4mj+qYMUpJ+8I0rTbY1dn21IXQBoBQmy8t1doKwmTdQ59F0FwZEPt/fGbRgBKVt3Quf6W 6n7kRk9MG6gdD7V9vPpFV41e+5MWYtqGWY3ScDP8SyYLjL/Xgr+5KFKkDfuubK8DeNqdLniV jHo/vqmIgO+6NgzPGPgmbutzFQXlxUqjiNAAKzF2+Tkddi+WKABrcc/EqnBb0X8GdqcIamO5 SyVmuM+7Zdns7D9pcV16zMMQ8LfNFQCDvbCuuQKMDg2F22x5ekYXpwjqTyfjcHBkWC8vFNoY 5aFMdyiN/Kkz0/kduP2ekYOgkRqcShfLEcG9SQ4LQZgqjMpTjSOGzBr3tOvVn5LkSJSHW2Z8 Q0dxSkvFG2/lsOWFbwQeeZSaBi5vRZCYCOf5tRd1+E93FyQfpt4vsrXshIAk7IK7f0qXvxP4 GDli5PKIEubD2Bn+gp3vB/DkfKySh5NBHVB+OPCoXRUWBkQxme65wBO02OZZt0k8Iq0i4Rci WV6z+lQHqDKtaVGgMsHn6PoeYhjf5Al5SP+U3imTjF2aCca1iDB5JOccX04MNljvifXgcbJN nkMgrzmm1ZgJ1PLur/ADWPlnz45quOhHg1TfUCLfI/DzgG7Z6u+oy4siQuFr9QT0MQIDAQAB o4HWMIHTMAkGA1UdEwQCMAAwEQYJYIZIAYb4QgEBBAQDAgWgMAsGA1UdDwQEAwIF4DAsBglg hkgBhvhCAQ0EHxYdT3BlblNTTCBHZW5lcmF0ZWQgQ2VydGlmaWNhdGUwHQYDVR0OBBYEFHw4 +LnuALyLA5Cgy7T5ZAX1WzKPMB8GA1UdIwQYMBaAFF3U3hpBZq40HB5VM7B44/gmXiI0MDgG CWCGSAGG+EIBAwQrFilodHRwczovL2N1ZGFzeXN0ZW1zLm5ldDoxMTQ0My9yZXZva2VkLmNy bDANBgkqhkiG9w0BAQUFAAOCAQEAZ0L4tQbBd0hd4wuw/YVqEBDDXJ54q2AoqQAmsOlnoxLO 31ehM/LvrTIP4yK2u1VmXtUumQ4Ao15JFM+xmwqtEGsh70RRrfVBAGd7KOZ3GB39FP2TgN/c L5fJKVxOqvEnW6cL9QtvUlcM3hXg8kDv60OB+LIcSE/P3/s+0tEpWPjxm3LHVE7JmPbZIcJ1 YMoZvHh0NSjY5D0HZlwtbDO7pDz9sZf1QEOgjH828fhtborkaHaUI46pmrMjiBnY6ujXMcWD pxtikki0zY22nrxfTs5xDWGxyrc/cmucjxClJF6+OYVUSaZhiiHfa9Pr+41okLgsRB0AmNwE f6ItY3TI8DGCBQowggUGAgEBMIGjMIGdMQswCQYDVQQGEwJVUzEQMA4GA1UECBMHRmxvcmlk YTESMBAGA1UEBxMJTmljZXZpbGxlMRkwFwYDVQQKExBDdWRhIFN5c3RlbXMgTExDMRwwGgYD VQQDExNDdWRhIFN5c3RlbXMgTExDIENBMS8wLQYJKoZIhvcNAQkBFiBjdXN0b21lci1zZXJ2 aWNlQGN1ZGFzeXN0ZW1zLm5ldAIBCDAJBgUrDgMCGgUAoIICOzAYBgkqhkiG9w0BCQMxCwYJ KoZIhvcNAQcBMBwGCSqGSIb3DQEJBTEPFw0xNDAzMjAxMjI2MzlaMCMGCSqGSIb3DQEJBDEW BBQR32SZybvYPRSh2yyMOKJNR5tQVDBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIG0BgkrBgEEAYI3EAQxgaYwgaMwgZ0xCzAJBgNV BAYTAlVTMRAwDgYDVQQIEwdGbG9yaWRhMRIwEAYDVQQHEwlOaWNldmlsbGUxGTAXBgNVBAoT EEN1ZGEgU3lzdGVtcyBMTEMxHDAaBgNVBAMTE0N1ZGEgU3lzdGVtcyBMTEMgQ0ExLzAtBgkq hkiG9w0BCQEWIGN1c3RvbWVyLXNlcnZpY2VAY3VkYXN5c3RlbXMubmV0AgEIMIG2BgsqhkiG 9w0BCRACCzGBpqCBozCBnTELMAkGA1UEBhMCVVMxEDAOBgNVBAgTB0Zsb3JpZGExEjAQBgNV BAcTCU5pY2V2aWxsZTEZMBcGA1UEChMQQ3VkYSBTeXN0ZW1zIExMQzEcMBoGA1UEAxMTQ3Vk YSBTeXN0ZW1zIExMQyBDQTEvMC0GCSqGSIb3DQEJARYgY3VzdG9tZXItc2VydmljZUBjdWRh c3lzdGVtcy5uZXQCAQgwDQYJKoZIhvcNAQEBBQAEggIAjrvvzQFOgSuCeTX+6e+W/0jShDsU MgxPnQc3xi002hY/qcA5mOQCAa/Dyynmcsyp1vYz27QaI7Bs9wiH+m+0U5x7gdp5H6mICMKe UGVkvDCQ/z2+sORuF+LilHmq6D/vy7i44s47wQ8WXCk6/a9TJXF6v83f1oxJuxqwUm13Sny8 xP/UQQXZZl/fv99j3B6jjiZZ9JfiTmhWDhb7e8OAFmgT68XAV5PHAYwvgSpaFxB3w/JCoolW scVL4n/ESFP26j3RxCYb4Zr0jidpX+aeBdzCtx5BJE4OBHcTM6tH011jbtCdiRe5ruhtZq0g j0//egwZgyOUTFMWGF4j3XB7qeC8pdv/W9PgdWUncn99kkgFfvi+QxtEe8EiKRc61VXSdt9R EwtNKrHbmvCkPNWlCQ78lw5j3lfSG6bwYbvwjc31/ZOlJ7kjEED4vvB70GSaFxeQTpGbMQwB kz5MpFlalj/w8XLy5AWcgENbs9VC4lVeqH78vgg9oVJznlHipQO2emnGWFpsReX3vK65gaTM 4i7a++zFX5uw/UabVTKdUvMyshX2pr++jeI2hK6h8FHqd8PVK/nhNYaOQVD+e/1ju8v6YJWu 4hQJDd44EleGDNXsEfm/FaZt6VNOZ+UZhvpfBdQaE+sE+DcTOhu/7eWIaiccO+s8tUFc+OCI CTp2VFQAAAAAAAA= --------------ms010203060907010901070002--
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