From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id E7047927 for ; Wed, 19 Jul 2017 07:35:27 +0000 (UTC) Received: from twosheds.infradead.org (twosheds.infradead.org [90.155.92.209]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 1D539AD for ; Wed, 19 Jul 2017 07:35:27 +0000 (UTC) Message-ID: <1500449720.19151.7.camel@infradead.org> From: David Woodhouse To: Mark Brown , Sergey Senozhatsky In-Reply-To: <20170620172738.zh4maxtfmlwhyrnt@sirena.org.uk> References: <20170619052146.GA2889@jagdpanzerIV.localdomain> <20170619103912.2edbf88a@gandalf.local.home> <20170619152055.GM3786@lunn.ch> <01a7d603-c0a2-7aae-8c8d-587063da5e61@suse.com> <20170619162317.4nxx6jsvuzvdtasz@sirena.org.uk> <20170620155825.GC409@tigerII.localdomain> <3908561D78D1C84285E8C5FCA982C28F612DAC67@ORSMSX114.amr.corp.intel.com> <20170620171134.GA444@tigerII.localdomain> <20170620172738.zh4maxtfmlwhyrnt@sirena.org.uk> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-3LQZQz+cmmvI0GPPTw69" Date: Wed, 19 Jul 2017 09:35:20 +0200 Mime-Version: 1.0 Cc: "ksummit-discuss@lists.linuxfoundation.org" Subject: Re: [Ksummit-discuss] [TECH TOPIC] printk redesign List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-3LQZQz+cmmvI0GPPTw69 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2017-06-20 at 18:27 +0100, Mark Brown wrote: > On Wed, Jun 21, 2017 at 02:11:34AM +0900, Sergey Senozhatsky wrote: >=20 > >=20 > > another thing that I found useful is a CPU number of the processor > > that stored a particular line to the logbuf. > > At some point we start reinventing ftrace...=C2=A0=C2=A0there's issues wi= th > joining the two up but there should at least be lessons we can learn. >=20 The other way of looking at this is "why are you abusing printk for stuff that should have been done via ftrace or other means instead". I confess I haven't got my curmudgeonly brain out of that mode at all, ever since realising that printk had been made asynchronous and unreliable (how long ago was that?) and that you could no longer see the dying gasp of a crashing kernel on its serial console. Rather than morphing printk into something more capable of bulk transport, I'd rather see it go back to its roots of debugging/diagnostics. The original complaint of "all this printk output makes things too slow" was better addressed by printing less or at lower severity (or adjusting the console loglevel), IMO. As things stand, the requirements for the various printk (ab)use cases seem to be contradictory =E2=80=94 if we're going to have a redesign then I think it would be good to take a holistic view and decide what it's actually *supposed* to be used for. And, perhaps more to the point, what it isn't supposed to be used for. --=-3LQZQz+cmmvI0GPPTw69 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCDzUw ggSvMIIDl6ADAgECAhEA4CPLFRKDU4mtYW56VGdrITANBgkqhkiG9w0BAQsFADBvMQswCQYDVQQG EwJTRTEUMBIGA1UEChMLQWRkVHJ1c3QgQUIxJjAkBgNVBAsTHUFkZFRydXN0IEV4dGVybmFsIFRU UCBOZXR3b3JrMSIwIAYDVQQDExlBZGRUcnVzdCBFeHRlcm5hbCBDQSBSb290MB4XDTE0MTIyMjAw MDAwMFoXDTIwMDUzMDEwNDgzOFowgZsxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVhdGVyIE1h bmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1pdGVkMUEw PwYDVQQDEzhDT01PRE8gU0hBLTI1NiBDbGllbnQgQXV0aGVudGljYXRpb24gYW5kIFNlY3VyZSBF bWFpbCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAImxDdp6UxlOcFIdvFamBia3 uEngludRq/HwWhNJFaO0jBtgvHpRQqd5jKQi3xdhTpHVdiMKFNNKAn+2HQmAbqUEPdm6uxb+oYep LkNSQxZ8rzJQyKZPWukI2M+TJZx7iOgwZOak+FaA/SokFDMXmaxE5WmLo0YGS8Iz1OlAnwawsayT QLm1CJM6nCpToxDbPSBhPFUDjtlOdiUCISn6o3xxdk/u4V+B6ftUgNvDezVSt4TeIj0sMC0xf1m9 UjewM2ktQ+v61qXxl3dnUYzZ7ifrvKUHOHaMpKk4/9+M9QOsSb7K93OZOg8yq5yVOhM9DkY6V3Rh UL7GQD/L5OKfoiECAwEAAaOCARcwggETMB8GA1UdIwQYMBaAFK29mHo0tCb3+sQmVO8DveAky1Qa MB0GA1UdDgQWBBSSYWuC4aKgqk/sZ/HCo/e0gADB7DAOBgNVHQ8BAf8EBAMCAYYwEgYDVR0TAQH/ BAgwBgEB/wIBADAdBgNVHSUEFjAUBggrBgEFBQcDAgYIKwYBBQUHAwQwEQYDVR0gBAowCDAGBgRV HSAAMEQGA1UdHwQ9MDswOaA3oDWGM2h0dHA6Ly9jcmwudXNlcnRydXN0LmNvbS9BZGRUcnVzdEV4 dGVybmFsQ0FSb290LmNybDA1BggrBgEFBQcBAQQpMCcwJQYIKwYBBQUHMAGGGWh0dHA6Ly9vY3Nw LnVzZXJ0cnVzdC5jb20wDQYJKoZIhvcNAQELBQADggEBABsqbqxVwTqriMXY7c1V86prYSvACRAj mQ/FZmpvsfW0tXdeDwJhAN99Bf4Ss6SAgAD8+x1banICCkG8BbrBWNUmwurVTYT7/oKYz1gb4yJj nFL4uwU2q31Ypd6rO2Pl2tVz7+zg+3vio//wQiOcyraNTT7kSxgDsqgt1Ni7QkuQaYUQ26Y3NOh7 4AEQpZzKOsefT4g0bopl0BqKu6ncyso20fT8wmQpNa/WsadxEdIDQ7GPPprsnjJT9HaSyoY0B7ks yuYcStiZDcGG4pCS+1pCaiMhEOllx/XVu37qjIUgAmLq0ToHLFnFmTPyOInltukWeh95FPZKEBom +nyK+5swggU9MIIEJaADAgECAhBqC1BYlVMtBFBN4igR/howMA0GCSqGSIb3DQEBCwUAMIGbMQsw CQYDVQQGEwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3Jk MRowGAYDVQQKExFDT01PRE8gQ0EgTGltaXRlZDFBMD8GA1UEAxM4Q09NT0RPIFNIQS0yNTYgQ2xp ZW50IEF1dGhlbnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTYxMjIwMDAwMDAwWhcN MTcxMjIwMjM1OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjAN BgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwbTrFaiGdvN2pThnR9q+4eaXB2wQZQNqhter5ZrJ pPO47e87bZ+f1tmYoh6+rB90G/XN24NErPRfvU4zVzNT9pCtCzSSVnBlZQBpaEYMKhcXo5PGKNsm An8BoGwNXjlxwbBNRaNO+ky0wNCaMNd1JLxEuvqg9J7rrcpHhWmnpXD5IKa8gv9GyVAJgOpiBOts p91sShc2kHvWJ5waPEWPCHDH9J+twGGKqKIIU7fdbURLUgUL1wlDSAHf/lgIAVCSj2H2HpoGqHpy HgOAClX9iRSLNa0Znj8HTaqfOwxXevsz1KkLFY+Ahm426GIEqdfkK2iT6Hhgc7tjNO3f8i5ALQID AQABo4IB8TCCAe0wHwYDVR0jBBgwFoAUkmFrguGioKpP7GfxwqP3tIAAwewwHQYDVR0OBBYEFILE dmHLtK6oxmFJZvBhTQhvqrS0MA4GA1UdDwEB/wQEAwIFoDAMBgNVHRMBAf8EAjAAMCAGA1UdJQQZ MBcGCCsGAQUFBwMEBgsrBgEEAbIxAQMFAjARBglghkgBhvhCAQEEBAMCBSAwRgYDVR0gBD8wPTA7 BgwrBgEEAbIxAQIBAQEwKzApBggrBgEFBQcCARYdaHR0cHM6Ly9zZWN1cmUuY29tb2RvLm5ldC9D UFMwXQYDVR0fBFYwVDBSoFCgToZMaHR0cDovL2NybC5jb21vZG9jYS5jb20vQ09NT0RPU0hBMjU2 Q2xpZW50QXV0aGVudGljYXRpb25hbmRTZWN1cmVFbWFpbENBLmNybDCBkAYIKwYBBQUHAQEEgYMw gYAwWAYIKwYBBQUHMAKGTGh0dHA6Ly9jcnQuY29tb2RvY2EuY29tL0NPTU9ET1NIQTI1NkNsaWVu dEF1dGhlbnRpY2F0aW9uYW5kU2VjdXJlRW1haWxDQS5jcnQwJAYIKwYBBQUHMAGGGGh0dHA6Ly9v Y3NwLmNvbW9kb2NhLmNvbTAeBgNVHREEFzAVgRNkd213MkBpbmZyYWRlYWQub3JnMA0GCSqGSIb3 DQEBCwUAA4IBAQA+AfvNhFwtapF5Lzjapgul3zYuEnMfR538Ya1vhP8wuOkcoJeT2gEFXzVO2WUu eWM0g0/DumnRB53htV/Qq/+vsL0i6a2+iOO7kHi5O7bZkgbdNv0t2lzonDUHi6LTa7NUj+tv+j6y hW+iNquC3ACP1dIZH8gJmicHblW63qRgp6wxhn315MLBeavi3uiSag2eeKFePiTIwJjN2UYq6kWg PL5G/Ycf9x/xN1XBTfJiURc0FsXhrA98VMWnt52C5Lo4txhGjzTI+IZg40b3YDs6E7mTYb5KKmbc QZA9priOFDdj1z5W9BdWhU6I/D0P9y8Z4Tr6+ZscMUVD0RqWy2LeMIIFPTCCBCWgAwIBAgIQagtQ WJVTLQRQTeIoEf4aMDANBgkqhkiG9w0BAQsFADCBmzELMAkGA1UEBhMCR0IxGzAZBgNVBAgTEkdy ZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMRQ09NT0RPIENBIExp bWl0ZWQxQTA/BgNVBAMTOENPTU9ETyBTSEEtMjU2IENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQg U2VjdXJlIEVtYWlsIENBMB4XDTE2MTIyMDAwMDAwMFoXDTE3MTIyMDIzNTk1OVowJDEiMCAGCSqG SIb3DQEJARYTZHdtdzJAaW5mcmFkZWFkLm9yZzCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoC ggEBAMG06xWohnbzdqU4Z0favuHmlwdsEGUDaobXq+WayaTzuO3vO22fn9bZmKIevqwfdBv1zduD RKz0X71OM1czU/aQrQs0klZwZWUAaWhGDCoXF6OTxijbJgJ/AaBsDV45ccGwTUWjTvpMtMDQmjDX dSS8RLr6oPSe663KR4Vpp6Vw+SCmvIL/RslQCYDqYgTrbKfdbEoXNpB71iecGjxFjwhwx/SfrcBh iqiiCFO33W1ES1IFC9cJQ0gB3/5YCAFQko9h9h6aBqh6ch4DgApV/YkUizWtGZ4/B02qnzsMV3r7 M9SpCxWPgIZuNuhiBKnX5Ctok+h4YHO7YzTt3/IuQC0CAwEAAaOCAfEwggHtMB8GA1UdIwQYMBaA FJJha4LhoqCqT+xn8cKj97SAAMHsMB0GA1UdDgQWBBSCxHZhy7SuqMZhSWbwYU0Ib6q0tDAOBgNV HQ8BAf8EBAMCBaAwDAYDVR0TAQH/BAIwADAgBgNVHSUEGTAXBggrBgEFBQcDBAYLKwYBBAGyMQED BQIwEQYJYIZIAYb4QgEBBAQDAgUgMEYGA1UdIAQ/MD0wOwYMKwYBBAGyMQECAQEBMCswKQYIKwYB BQUHAgEWHWh0dHBzOi8vc2VjdXJlLmNvbW9kby5uZXQvQ1BTMF0GA1UdHwRWMFQwUqBQoE6GTGh0 dHA6Ly9jcmwuY29tb2RvY2EuY29tL0NPTU9ET1NIQTI1NkNsaWVudEF1dGhlbnRpY2F0aW9uYW5k U2VjdXJlRW1haWxDQS5jcmwwgZAGCCsGAQUFBwEBBIGDMIGAMFgGCCsGAQUFBzAChkxodHRwOi8v Y3J0LmNvbW9kb2NhLmNvbS9DT01PRE9TSEEyNTZDbGllbnRBdXRoZW50aWNhdGlvbmFuZFNlY3Vy ZUVtYWlsQ0EuY3J0MCQGCCsGAQUFBzABhhhodHRwOi8vb2NzcC5jb21vZG9jYS5jb20wHgYDVR0R BBcwFYETZHdtdzJAaW5mcmFkZWFkLm9yZzANBgkqhkiG9w0BAQsFAAOCAQEAPgH7zYRcLWqReS84 2qYLpd82LhJzH0ed/GGtb4T/MLjpHKCXk9oBBV81TtllLnljNINPw7pp0Qed4bVf0Kv/r7C9Iumt vojju5B4uTu22ZIG3Tb9Ldpc6Jw1B4ui02uzVI/rb/o+soVvojargtwAj9XSGR/ICZonB25Vut6k YKesMYZ99eTCwXmr4t7okmoNnnihXj4kyMCYzdlGKupFoDy+Rv2HH/cf8TdVwU3yYlEXNBbF4awP fFTFp7edguS6OLcYRo80yPiGYONG92A7OhO5k2G+Sipm3EGQPaa4jhQ3Y9c+VvQXVoVOiPw9D/cv GeE6+vmbHDFFQ9Ealsti3jGCA9MwggPPAgEBMIGwMIGbMQswCQYDVQQGEwJHQjEbMBkGA1UECBMS R3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYDVQQKExFDT01PRE8gQ0Eg TGltaXRlZDFBMD8GA1UEAxM4Q09NT0RPIFNIQS0yNTYgQ2xpZW50IEF1dGhlbnRpY2F0aW9uIGFu ZCBTZWN1cmUgRW1haWwgQ0ECEGoLUFiVUy0EUE3iKBH+GjAwDQYJYIZIAWUDBAIBBQCgggHzMBgG CSqGSIb3DQEJAzELBgkqhkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTE3MDcxOTA3MzUyMFowLwYJ KoZIhvcNAQkEMSIEIC2Cxi9AiOODCrysneNBcnqfi5f/bhz7pMnEJ5pgBqKnMIHBBgkrBgEEAYI3 EAQxgbMwgbAwgZsxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAO BgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1pdGVkMUEwPwYDVQQDEzhDT01P RE8gU0hBLTI1NiBDbGllbnQgQXV0aGVudGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQQIQagtQ WJVTLQRQTeIoEf4aMDCBwwYLKoZIhvcNAQkQAgsxgbOggbAwgZsxCzAJBgNVBAYTAkdCMRswGQYD VQQIExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9E TyBDQSBMaW1pdGVkMUEwPwYDVQQDEzhDT01PRE8gU0hBLTI1NiBDbGllbnQgQXV0aGVudGljYXRp b24gYW5kIFNlY3VyZSBFbWFpbCBDQQIQagtQWJVTLQRQTeIoEf4aMDANBgkqhkiG9w0BAQEFAASC AQApcbXHKJLO3fZBOX3TAoEMoBeY3G5/hd+lj6x06cDC6kWg41d6kVfOXY8wzH6idsO0i9lNWMtJ tERhOEo6eLvQW7dtbn28Z1GYZBJEaFBERWSfVOnvi2tx7OPxJXpOX/XROww2V+UkDUKtZpT71pSo ovUKvyKIJ1eBdr5OOi4wPnMkzgaTpcFqbERnKgbpmyMltgfnu+TTzE4511H0HoCSjg2Fu1iH90mr YT0S99s1vp/DGdx5/6mEJ6BeMyKfnLe+8I07DIdHKjYzN/k1+PfhOO4FVLas7l4yA6PJBgblDN5g Se6mHoWLzOTNoVbTsn0Ws290nUqx+T7GLylRdqNEAAAAAAAA --=-3LQZQz+cmmvI0GPPTw69--