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

Ingo Molnar
2009-02-22T17:14:03Z

* 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