Date: Thu, 19 Apr 2018 16:17:41 -0700 (PDT) From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net> To: cem@freebsd.org Cc: Konstantin Belousov <kostikbel@gmail.com>, Colin Percival <cperciva@tarsnap.com>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: RFC: Hiding per-CPU kernel output behind bootverbose Message-ID: <201804192317.w3JNHfB9067875@pdx.rh.CN85.dnsmgr.net> In-Reply-To: <CAG6CVpUerOo%2B55nJq61Hy83RYpbOZS6puEDuemspfNS12urZZw@mail.gmail.com>
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> On Thu, Apr 19, 2018 at 1:44 PM, Konstantin Belousov > <kostikbel@gmail.com> wrote: > > On Thu, Apr 19, 2018 at 06:06:21PM +0000, Colin Percival wrote: > >> On large systems (e.g., EC2's x1e.32xlarge instance type, with 128 vCPUs) > >> the boot time console output contains a large number of lines of the forms > >> > >> SMP: AP CPU #N Launched! > >> cpuN: <ACPI CPU> on acpi0 > >> estN: <Enhanced SpeedStep Frequency Control> on cpuN > >> > >> Having 128 almost-identical lines of output doesn't seem very useful, and > >> it actually has a nontrivial impact on the time spent booting. > >> > >> Does anyone mind if I hide these by default, having them only show up if > >> boot verbosity is requested? > > +1. For the device attaches, perhaps it makes sense to add a device > 'spammy' flag, and set it for per-CPU devices like cpuN or estN. Then > the generic attach code can choose whether to print spammy attaches > based on bootverbose. dmesg for device attaches seems mostly > redundant with devinfo(8) for persistent devices like ACPI CPU and > est(4). > > > The 'CPU XX Launched' messages are very useful for initial diagnostic > > of the SMP startup failures. You need to enable bootverbose to see the > > hang details, but for initial hint they are required. Unfortunately, AP > > startup hangs occur too often to pretend that this can be delegated to > > very specific circumstances. > > Really? I don't know that I've ever seen an AP startup hang. How > often do they occur? > What about if XX > 4 silence the messages unless bootverbose is set? That gets us kinda both worlds, you still see AP startup occuring, but once you seen 4 of them go off there isnt much point in seeing the next N of them. -- Rod Grimes rgrimes@freebsd.org
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