Re: [PATCH] tracing/markers: make markers select tracepoints

From: Ingo Molnar <mingo@elte.hu>
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Avi Kivity <avi@redhat.com>,
	Randy Dunlap <randy.dunlap@oracle.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org
Subject: Re: [PATCH] tracing/markers: make markers select tracepoints
Date: Sun, 22 Feb 2009 18:13:44 +0100	[thread overview]
Message-ID: <20090222171344.GC6570@elte.hu> (raw)
In-Reply-To: <y0mtz6nqwe9.fsf@ton.toronto.redhat.com>

* Frank Ch. Eigler <fche@redhat.com> wrote:

> Ingo Molnar <mingo@elte.hu> writes:
> 
> > [...]
> > there's i think the KVM usecase where markers are used 
> > essentially a printk()-alike flexible tracing facility.
> >
> > [...]
> > ./vmx.c:	KVMTRACE_3D(MSR_READ, vcpu, ecx, (u32)data, (u32)(data >> 32),
> > ./vmx.c:	KVMTRACE_3D(MSR_WRITE, vcpu, ecx, (u32)data, (u32)(data >> 32),
> > ./vmx.c:	KVMTRACE_0D(PEND_INTR, vcpu, handler);
> >
> > I think this could easily be converted to a wrapper around 
> > ftrace_printk() plus a "kvmtrace" ftrace plugin [...]
> 
> It would be even easier converted to the markers API directly,
> without the KVMTRACE* macro intermediary:
> 
> before:
>         KVMTRACE_3D(MSR_READ, &svm->vcpu, ecx, (u32)data,
>                     (u32)(data >> 32), handler);
> after:
> 	trace_mark(kvmtrace, "MSR_READ: %p, %08lx, %016Lx\n",
>                              &svm->vcpu, ecx, data);
> 
> All this already "just works".

except that we are removing markers.

	Ingo