From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergey Senozhatsky Subject: Re: Serial console is causing system lock-up Date: Fri, 8 Mar 2019 10:22:42 +0900 Message-ID: <20190308012242.GA4063@jagdpanzerIV> References: <20190306152218.eocv4zulf7tv2mkc@pathway.suse.cz> <20190306163003.GA31858@mit.edu> <20190306171943.12345598@oasis.local.home> <87ftrzbp3y.fsf@linutronix.de> <23681.9703.524330.948156@quad.stoffel.home> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mikulas Patocka Cc: Petr Mladek , Nigel Croxon , "Theodore Y. Ts'o" , John Ogness , Greg Kroah-Hartman , John Stoffel , Steven Rostedt , Sergey Senozhatsky , dm-devel@redhat.com, linux-serial@vger.kernel.org List-Id: linux-serial@vger.kernel.org On (03/07/19 09:26), Mikulas Patocka wrote: > On Thu, 7 Mar 2019, John Stoffel wrote: > > > The real problem is the disconnect between serial console speed and > > capacity in bits/sec and that of the regular console. Serial, esp at > > 9600 baud is just a slow and limited resource which needs to be > > handled differently than a graphical console. > > > > I'm also big on ratelimiting messages, even critical warning > > messages. Too much redundant info doesn't help anyone. And what a > > subsystem thinks is critical, may not be critical to the system as a > > whole. > > Perhaps a proper solution would be to drop excessive messages to serial > console unless Oops or BUG has happened? Technically, we can have a per-console loglevel configuration. We have several use cases for this already. Slower consoles will filter out more messages and print only ERR/CRIT/ALERT/EMERG. dm-integrity uses WARN level, which is below ERR; so it seems that per-console loglevel can do the trick. -ss