Date: Fri, 12 Aug 2022 13:43:09 +0000 From: John F Carr <jfc@mit.edu> To: freebsd-arm <freebsd-arm@freebsd.org> Subject: Slow crash dump speed on ARM server Message-ID: <A38C5C79-FC70-4C2D-929B-1D8E1F48DC9E@mit.edu>
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--Apple-Mail=_7018BA2A-D1FA-4FD1-9EF8-AF507BB0CA06 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii My Ampere eMAG server takes about two hours to save a crash dump after = panic, a write speed of about 3 MB/s to an NVMe SSD that is capable of = hundreds of times the performance if not a thousand times. Is this = normal? Does a crash dump write tiny blocks using synchronous writes or = something like that? /var/crash/info.last has Blocksize: 512 Compression: none The blocksize is suspicious. Is the kernel writing 512 bytes at a time = to an SSD with native 4K blocks? That would be bad. Is there a sysctl parameter I can set to make writes faster? I did want = the dump this time but this performance would not be acceptable for a = production server. (Math: "Dumping 16023 out of 130745 MB" took ~6000 seconds. A 20 GB = dump took over 2 hours.)= --Apple-Mail=_7018BA2A-D1FA-4FD1-9EF8-AF507BB0CA06 Content-Disposition: attachment; filename="smime.p7s" Content-Type: application/pkcs7-signature; name=smime.p7s Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCA7sw ggO3MIIDIKADAgECAhEAllRUaZWy44T/aVEsqzSrczANBgkqhkiG9w0BAQsFADBsMQswCQYDVQQG EwJVUzEWMBQGA1UECBMNTWFzc2FjaHVzZXR0czEuMCwGA1UEChMlTWFzc2FjaHVzZXR0cyBJbnN0 aXR1dGUgb2YgVGVjaG5vbG9neTEVMBMGA1UECxMMQ2xpZW50IENBIHYxMB4XDTIyMDcwNTE2NTQ0 NVoXDTIzMDczMDE2NTQ0NVowgZ4xCzAJBgNVBAYTAlVTMRYwFAYDVQQIEw1NYXNzYWNodXNldHRz MS4wLAYDVQQKEyVNYXNzYWNodXNldHRzIEluc3RpdHV0ZSBvZiBUZWNobm9sb2d5MRUwEwYDVQQL EwxDbGllbnQgQ0EgdjExFDASBgNVBAMTC0pvaG4gRiBDYXJyMRowGAYJKoZIhvcNAQkBFgtqZmNA TUlULkVEVTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAL2Ka5+9REw1B9JXThajulqv SjDFK1pNpGB2nljRQy5iTTTVddq/4+s+uC88etHWbMquFd/i9sCIxLHgDFhlGZRhcORhzDfwIxLA P8q4KMsAPeXO2kgh86pGH+DEsUPEbEtdkN2cnT9kt+BE2cPCOiqAR+YBWZX3ebDLc4+eWiPfErg7 WEr4XcIraxxxtLuUR6sVbN7nG7WCtBCalzbAxryy5GmWZ1z4OawzylJVb+qLKeMi3XN+H/d+shdm 6PmyqGeCu7jpN3+g/eAuWk/PWhIUhDwABK9JGWW2+xWCtDHxutzRt8vDMZK2GaE6MzpBpTFR1P1o IdodVtrHGtVnKq0CAwEAAaOBoTCBnjAJBgNVHRMEAjAAMBEGCWCGSAGG+EIBAQQEAwIFoDAdBgNV HSUEFjAUBggrBgEFBQcDBAYIKwYBBQUHAwIwCwYDVR0PBAQDAgXgMB0GA1UdDgQWBBQCc+0gYnBj WRsOZgQ78pmO+ojOaDAzBgNVHR8ELDAqMCigJqAkhiJodHRwOi8vY2EubWl0LmVkdS9jYS9taXRj bGllbnQuY3JsMA0GCSqGSIb3DQEBCwUAA4GBAAm/9fT9H4n5ks4q9cGE5FWIwAQmEGre6gMVU+VL V4p2Qfd4eZki0uKg+Vi6BWeHL2GMQQpnpjgm1Xx6q7oSruPTkkrs75X7oTW5Nf550U5qEKXSqboK y+6dkw8fNvNci0tYs0j+Ev6JPU4VgDK/NSWtRFrndFzLI2SgJ6k+Ess4MYIDRjCCA0ICAQEwgYEw bDELMAkGA1UEBhMCVVMxFjAUBgNVBAgTDU1hc3NhY2h1c2V0dHMxLjAsBgNVBAoTJU1hc3NhY2h1 c2V0dHMgSW5zdGl0dXRlIG9mIFRlY2hub2xvZ3kxFTATBgNVBAsTDENsaWVudCBDQSB2MQIRAJZU VGmVsuOE/2lRLKs0q3MwDQYJYIZIAWUDBAIBBQCgggGVMBgGCSqGSIb3DQEJAzELBgkqhkiG9w0B BwEwHAYJKoZIhvcNAQkFMQ8XDTIyMDgxMjEzNDMwOFowLwYJKoZIhvcNAQkEMSIEINfhHXWfxJmm a2eW0q2uwD0Z7t+pqxTreD/mlOM+CbjwMIGSBgkrBgEEAYI3EAQxgYQwgYEwbDELMAkGA1UEBhMC VVMxFjAUBgNVBAgTDU1hc3NhY2h1c2V0dHMxLjAsBgNVBAoTJU1hc3NhY2h1c2V0dHMgSW5zdGl0 dXRlIG9mIFRlY2hub2xvZ3kxFTATBgNVBAsTDENsaWVudCBDQSB2MQIRAJZUVGmVsuOE/2lRLKs0 q3MwgZQGCyqGSIb3DQEJEAILMYGEoIGBMGwxCzAJBgNVBAYTAlVTMRYwFAYDVQQIEw1NYXNzYWNo dXNldHRzMS4wLAYDVQQKEyVNYXNzYWNodXNldHRzIEluc3RpdHV0ZSBvZiBUZWNobm9sb2d5MRUw EwYDVQQLEwxDbGllbnQgQ0EgdjECEQCWVFRplbLjhP9pUSyrNKtzMA0GCSqGSIb3DQEBCwUABIIB AGaHafwp8B8wfc/U5/tqJDWTRGwht7fQawQCOyVAsOmBONOlQEcSQavdrk0W3tT8D54qaas46ltk boRv7TbP4sHM13xsvSGIHmxAotlVqStlS0aCeyZG6erd9gwUn67e/A3s/m9GQ3aFzgLzTPq/5+39 LQn7ikVegmnRbmkaHALGfjjmXh/q20pwuUpQbjLOZU5gI+lMCZTLPJV8jJO7kmKGFnmh7crWmaZb nSZtBZfunwpX2y66I0C9nDlXsFLrQIGaTXCYFUUGPPjIcMx3riJj6gHdAfQA7OKtcqUVBdiDhnJt 78IM+1kDgYLl0alDFTCvYY1szrugGJJiKxpaaV8AAAAAAAA= --Apple-Mail=_7018BA2A-D1FA-4FD1-9EF8-AF507BB0CA06--
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