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Message-ID: <20090305091611.GB16026@elte.hu>
Date: Thu, 5 Mar 2009 10:16:11 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Frederic Weisbecker <fweisbec@...il.com>
Cc: prasad@...ux.vnet.ibm.com,
Andrew Morton <akpm@...ux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Alan Stern <stern@...land.harvard.edu>,
Roland McGrath <roland@...hat.com>
Subject: Re: [patch 11/11] ftrace plugin for kernel symbol tracing using HW
Breakpoint interfaces
* Frederic Weisbecker <fweisbec@...il.com> wrote:
> On Thu, Mar 05, 2009 at 10:13:33AM +0530, prasad@...ux.vnet.ibm.com wrote:
> > This patch adds an ftrace plugin to detect and profile memory access over
> > kernel variables. It uses HW Breakpoint interfaces to 'watch memory
> > addresses.
> >
> > Signed-off-by: K.Prasad <prasad@...ux.vnet.ibm.com>
> > ---
>
>
> Hi,
>
> Nice feature. And moreover the standardized hardware
> breakpoints could be helpful for tracing.
yeah. The feature is much more alive now.
> Just some comments below.
One other thing:
+#ifdef CONFIG_FTRACE_SELFTEST
+int trace_selftest_startup_ksym(struct tracer *trace, struct trace_array *tr)
+{
+ /* TODO: Will be implemented later */
+ return 0;
+}
+#endif /* CONFIG_FTRACE_SELFTEST */
This needs to be implemented before i can pick the code up into
tip:tracing, as otherwise we will not notice it fast enough if
some of this stuff breaks.
Basically the ftrace plugin will be the main usage vector of
this facility, so the self-test is a must-have.
Looks very nice otherwise.
Ingo
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