[Qemu-devel] Re: [PATCH 7/7] trace: Trace virtqueue operations

[Stefan Hajnoczi]

On Tue, May 25, 2010 at 1:04 PM, Avi Kivity <address@hidden> wrote:
> Those %ps are more or less useless.  We need better ways of identifying
> them.

You're right, the vq pointer is useless in isolation.  We don't know
which virtio device or which virtqueue number.

With the full context of a trace it would be possible to correlate the
vq pointer if we had trace events for vdev and vq setup.

Adding custom formatters is could be tricky since the format string is
passed only to tracing backends that use it, like UST.  And UST uses
its own sprintf implementation which we don't have direct control
over.

I think we just need to guarantee that any pointer can be correlated
with previous trace entries that give context for that pointer.

Stefan