Date: Sat, 21 Apr 2018 20:30:10 +0000 From: Colin Percival <cperciva@tarsnap.com> To: Warner Losh <imp@bsdimp.com> Cc: Konstantin Belousov <kib@freebsd.org>, Conrad Meyer <cem@freebsd.org>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: RFC: Hiding per-CPU kernel output behind bootverbose Message-ID: <01000162e9e65aa9-50a58dbb-eaae-45fb-b6bb-20212b25d016-000000@email.amazonses.com> In-Reply-To: <CANCZdfoNuN%2BECCnTkWufWeGD2HOFbvM4S5eGmDzHV8JGT1M2ag@mail.gmail.com> References: <01000162df15f856-1e5d2641-2a72-4250-8d8e-adcd47bc5db4-000000@email.amazonses.com> <20180419204405.GE6887@kib.kiev.ua> <CAG6CVpUerOo%2B55nJq61Hy83RYpbOZS6puEDuemspfNS12urZZw@mail.gmail.com> <20180419214550.GF6887@kib.kiev.ua> <01000162e58a4670-66a9983e-c3ef-493a-a60f-c477645b5100-000000@email.amazonses.com> <CANCZdfoNuN%2BECCnTkWufWeGD2HOFbvM4S5eGmDzHV8JGT1M2ag@mail.gmail.com>
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On 04/21/18 10:02, Warner Losh wrote: > On Fri, Apr 20, 2018 at 6:11 PM, Colin Percival <cperciva@tarsnap.com > <mailto:cperciva@tarsnap.com>> wrote: > Would it be sufficient for debugging purposes if I change the !bootverbose > case from printing many lines of > > SMP: AP CPU #N Launched! > > to instead have a single > > SMP: Launching AP CPUs: 86 73 111 21 8 77 100 28 57 42 10 60 87 88 41 113 36 > 19 72 46 92 52 24 81 90 3 107 96 9 14 80 118 29 121 62 74 56 55 1 12 63 18 67 > 13 45 102 33 94 69 68 93 83 48 31 30 32 51 89 71 78 64 84 123 61 40 47 37 22 > 54 101 38 4 97 44 17 109 104 5 85 43 2 99 39 65 95 53 58 66 91 125 23 115 16 > 35 79 112 103 82 7 75 11 6 98 15 126 127 20 70 34 105 27 50 116 120 49 25 108 > 106 122 117 114 26 110 59 76 124 119 > > ? (With each AP printing its number as it reaches the appropriate point?) > > This yields almost the same gain as silencing the launch messages completely, > while still allowing you to see each CPU announcing itself. > > The trouble is that you've got N CPUs that are doing output at the same time. > You'll need to synchronize somehow. And how do you know that the last one is > done? Especailly if one of the CPUs doesn't start.. Fortunately, this output is all generated with the ap_boot_mtx lock held. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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