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Subject: Re: [PATCH 01/20 -v5] printk - dont wakeup klogd with interrupts
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From: Daniel Walker <dwalker@mvista.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
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On Wed, 2008-01-23 at 13:43 -0500, Steven Rostedt wrote:
> On Wed, 23 Jan 2008, Daniel Walker wrote:
> 
> >
> > On Wed, 2008-01-23 at 13:18 -0500, Steven Rostedt wrote:
> >
> > > The wakeup hook in schedule is when we find out that we hit our max. I
> > > could postpone that somehow, but that would require more glue code than I
> > > would like to add.
> >
> > Which hook specifically ?
> 
> The wakeup tracer does a print on max when the new task is about to be
> switched to (in context_switch).

You can't move that hook to when the task actually starts running (i.e.
at the end of schedule() )..

> >
> > > As for -rt, we've disabled printk for consoles not ATOMIC safe. So the
> > > only consoles that will print in atomic sections so far are, earlyprintk
> > > and the VGA.
> >
> > Is this code you added recently for tracing?
> 
> Nope, it's been there for a few releases and had nothing to do with the
> latency tracer.
> 
> <looks at code>
> 
> Hmm, seems that only the "hack" fix is in upstream. The Red Hat version
> has the better fix, but mainline didn't get it. OK, I'll add that to the
> next -rt release.

mainline ? The problem I'm thinking of was directly tracing related..

Daniel

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