Re: [PATCH 4/4] tracing, page-allocator: Add a postprocessing script for page-allocator-related ftrace events

From: Valdis.Kletnieks@vt.edu
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	penberg@cs.helsinki.fi, a.p.zijlstra@chello.nl,
	fweisbec@gmail.com, rostedt@goodmis.org, mel@csn.ul.ie,
	lwoodman@redhat.com, riel@redhat.com, peterz@infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 4/4] tracing, page-allocator: Add a postprocessing script for page-allocator-related ftrace events
Date: Wed, 05 Aug 2009 11:07:19 -0400	[thread overview]
Message-ID: <16859.1249484839@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Tue, 04 Aug 2009 13:18:18 PDT." <20090804131818.ee5d4696.akpm@linux-foundation.org>

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On Tue, 04 Aug 2009 13:18:18 PDT, Andrew Morton said:

> As usual, we're adding tracepoints because we feel we must add
> tracepoints, not because anyone has a need for the data which they
> gather.

One of the strong points of the Solaris 'dtrace' is that the kernel comes
pre-instrumented with zillions of tracepoints, including a lot that don't
seem to have very much application - just so they're already in place in
case you hit some weird issue and need the tracepoint for an ad-crock dtrace
script to debug something.  So when I'm trying to diagnose why my backup
server suddenly got sluggish 3 terabytes into a 5 terabyte backup, and it
looks like some weird fiberchannel issue, I can collect data without having
to reboot to install a tracepoint (which would lose the backup, and possibly
reset the issue or otherwise make it go into hiding).

Just sayin'. :)

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