netdev - Re: [PATCH] tcp FRTO: in-order-only "TCP proxy" fragility workaround (fwd)

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Date:	Sun, 5 Oct 2008 14:52:50 -0300
From:	Dâniel Fraga <fragabr@...il.com>
To:	"Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	David Miller <davem@...emloft.net>,
	Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] tcp FRTO: in-order-only "TCP proxy" fragility
 workaround (fwd)

On Fri, 3 Oct 2008 00:19:08 +0300 (EEST)
"Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi> wrote:

> On Thu, 2 Oct 2008, Dâniel Fraga wrote:
> 
> > On Thu, 2 Oct 2008 23:31:28 +0300 (EEST)
> > "Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi> wrote:
> > 
> > > Ah, I was kind of thinking that you were doing something net related 
> > > using some raw socket thing (such as traceroute) when you earlier 
> > > mentioned sudo (iirc, we never really discussed what you usually do with 
> > > it when you see the stall).
> > 
> > 	I read nntp groups everyday and I use leafnode. The stall on my
> > desktop happens when I run fetchnews (which must be run as user "news"
> > so I have to use sudo). Usually the stall on my desktop happens when
> > I'm using fetchnews or some other command run by sudo.
> 
> Yes yes, I'd be specificly interested to have some rough idea what that
> "some other command" includes, especially as some seem to be non-net 
> related since you mentioned e.g., that /dev/log thing?

	Here we go folks, good and bad news:

1) the good news is that the Thomas' patch detected the stall, but...

2)

Oct  5 14:23:03 teleporto vmunix: Tracer stopped
Oct  5 14:23:13 teleporto last message repeated 2 times

	if it had really stopped, the message wouldn't be repeated 2
times.

	and

fraga@...eporto ~$ cat /debug/tracing/tracing_enabled 
1

	In other words, the tracing wasn't really stopped.

	So I couldn't get what Thomas want. Should I activated the
initial auto-checking of ftrace to see if it's really working? Very
strange the fact it wasn't stopped.

	***

	I was waiting for 2 days to a stall and I managed to get the
stall by using "sudo" multiple times. It seems that sudo really makes
this bug hit.
	
	And now? Should we revise Thomas patch? Maybe a bug in ftrace
code that prevents it from being stopped? It seems that:

ftrace_enabled = 0;

	isn't really stopping the tracing.

	Thank you.

-- 
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