Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752441AbaDXTza (ORCPT ); Thu, 24 Apr 2014 15:55:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:38955 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751246AbaDXTz2 (ORCPT ); Thu, 24 Apr 2014 15:55:28 -0400 Date: Thu, 24 Apr 2014 12:58:21 -0700 From: Greg Kroah-Hartman To: =?iso-8859-1?Q?J=F6rn?= Engel Cc: Jiri Kosina , Rik van Riel , linux-kernel@vger.kernel.org, peterz@infradead.org, akpm@linux-foundation.org, cxie@redhat.com, Jiri Slaby Subject: Re: [PATCH] printk: Print cpu number along with time Message-ID: <20140424195821.GA3092@kroah.com> References: <20140423125352.704f9fb2@annuminas.surriel.com> <20140424005247.GA17713@logfs.org> <20140424194024.GA25446@logfs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140424194024.GA25446@logfs.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 24, 2014 at 03:40:24PM -0400, J?rn Engel wrote: > On Wed, 23 April 2014 20:52:47 -0400, J?rn Engel wrote: > > > > I use the patch below for some time now. While it doesn't avoid the > > log pollution in the first place, it lessens the impact somewhat. > > Added a config option and ported it to current -linus. Andrew, would > you take this patch? > > --- > > Sometimes the printk log is heavily interleaving between different cpus. > This is particularly bad when you have two backtraces at the same time, > but can be annoying in other cases as well. With an explicit cpu > number, a simple grep can disentangle the mess for you. > > Signed-off-by: Joern Engel > --- > kernel/printk/printk.c | 19 ++++++++++++++++--- > lib/Kconfig.debug | 9 +++++++++ > 2 files changed, 25 insertions(+), 3 deletions(-) > > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index a45b50962295..b9e464924825 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -200,6 +200,7 @@ struct printk_log { > u16 len; /* length of entire record */ > u16 text_len; /* length of text buffer */ > u16 dict_len; /* length of dictionary buffer */ > + u16 cpu; /* cpu the message was generated on */ > u8 facility; /* syslog facility */ > u8 flags:5; /* internal record flags */ > u8 level:3; /* syslog level */ > @@ -346,6 +347,7 @@ static void log_store(int facility, int level, > msg->facility = facility; > msg->level = level & 7; > msg->flags = flags & 0x1f; > + msg->cpu = smp_processor_id(); > if (ts_nsec > 0) > msg->ts_nsec = ts_nsec; > else > @@ -859,7 +861,7 @@ static bool printk_time; > #endif > module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); > > -static size_t print_time(u64 ts, char *buf) > +static size_t print_time(u64 ts, u16 cpu, char *buf) > { > unsigned long rem_nsec; > > @@ -868,11 +870,20 @@ static size_t print_time(u64 ts, char *buf) > > rem_nsec = do_div(ts, 1000000000); > > +#ifdef CONFIG_PRINTK_CPU > + if (!buf) > + return snprintf(NULL, 0, "[%5lu.000000,%02x] ", %02x for a cpu? What happens on machines with 8k cpus? And is this really an issue? Debugging by using printk is fun, but not really something that people need to add a cpu number to. Why not just use a tracepoint in your code to get the needed information instead? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/