From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCHSET] printk, netconsole: implement reliable netconsole Date: Fri, 17 Apr 2015 14:07:32 -0400 Message-ID: <20150417180732.GF16743@htj.duckdns.org> References: <20150417162826.GB16743@htj.duckdns.org> <20150417.131712.1245246947203158168.davem@davemloft.net> <20150417173754.GC16743@htj.duckdns.org> <201504180243.IDB78159.tFVOOFQFSOHLMJ@I-love.SAKURA.ne.jp> <20150417174522.GD16743@htj.duckdns.org> <201504180303.GAB26011.OLJFSMVFFOHtOQ@I-love.SAKURA.ne.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Tetsuo Handa Return-path: Content-Disposition: inline In-Reply-To: <201504180303.GAB26011.OLJFSMVFFOHtOQ@I-love.SAKURA.ne.jp> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Sat, Apr 18, 2015 at 03:03:46AM +0900, Tetsuo Handa wrote: > If you tolerate loss of kernel messages, adding sequence number to each UDP Well, there's a difference between accepting loss when log buffer overflows and when any packets get lost. > packet will be sufficient for finding out whether the packets were lost and/or > reordered in flight. > > printk("Hello"); > => netconsole sends "00000000 Hello" using UDP > printk("netconsole"); > => netconsole sends "00000001 netconsole" using UDP > printk("world\n"); > => netconsole sends "00000002 world\n" using UDP > > It might be nice to allow administrator to prefix a sequence number > to netconsole messages for those who are using special receiver > program (e.g. ncrx) which checks that sequence number. That said, this is pretty much what the first 12 patches do (except for the last printk patch, which can be taken out). We already have sequencing and established format to expose them to userland - try cat /dev/kmsg, which btw is what local loggers on modern systems use anyway. Why introduce netconsole's own version of metadata? Thanks. -- tejun