From owner-freebsd-hackers@freebsd.org Thu Apr 19 23:17:46 2018 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 39A24FAB245 for ; Thu, 19 Apr 2018 23:17:46 +0000 (UTC) (envelope-from freebsd-rwg@pdx.rh.CN85.dnsmgr.net) Received: from pdx.rh.CN85.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 8BC9D76A19; Thu, 19 Apr 2018 23:17:45 +0000 (UTC) (envelope-from freebsd-rwg@pdx.rh.CN85.dnsmgr.net) Received: from pdx.rh.CN85.dnsmgr.net (localhost [127.0.0.1]) by pdx.rh.CN85.dnsmgr.net (8.13.3/8.13.3) with ESMTP id w3JNHftp067876; Thu, 19 Apr 2018 16:17:41 -0700 (PDT) (envelope-from freebsd-rwg@pdx.rh.CN85.dnsmgr.net) Received: (from freebsd-rwg@localhost) by pdx.rh.CN85.dnsmgr.net (8.13.3/8.13.3/Submit) id w3JNHfB9067875; Thu, 19 Apr 2018 16:17:41 -0700 (PDT) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <201804192317.w3JNHfB9067875@pdx.rh.CN85.dnsmgr.net> Subject: Re: RFC: Hiding per-CPU kernel output behind bootverbose In-Reply-To: To: cem@freebsd.org Date: Thu, 19 Apr 2018 16:17:41 -0700 (PDT) CC: Konstantin Belousov , Colin Percival , "freebsd-hackers@freebsd.org" X-Mailer: ELM [version 2.4ME+ PL121h (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Apr 2018 23:17:46 -0000 > On Thu, Apr 19, 2018 at 1:44 PM, Konstantin Belousov > 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: on acpi0 > >> estN: 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