Re: [PATCH 1/2] trace: document how to specify multiple --trace patterns

[Philippe Mathieu-Daudé]

On 1/12/21 5:58 PM, Stefan Hajnoczi wrote:
> It is possible to repeat the --trace option to specify multiple
> patterns. This may be preferrable to users who do not want to create a
> file with a list of patterns.
> 
> Suggested-by: BALATON Zoltan <balaton@eik.bme.hu>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  docs/devel/tracing.rst | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/docs/devel/tracing.rst b/docs/devel/tracing.rst
> index 4ebf8e38ea..8777c19d14 100644
> --- a/docs/devel/tracing.rst
> +++ b/docs/devel/tracing.rst
> @@ -22,10 +22,15 @@ events::
>  This output comes from the "log" trace backend that is enabled by default 
> when
>  ``./configure --enable-trace-backends=BACKENDS`` was not explicitly 
> specified.
>  
> -More than one trace event pattern can be specified by providing a file
> -instead::
> +Multiple patterns can be specified by repeating the ``--trace`` option::
> +
> +    $ qemu --trace "kvm_*" --trace "virtio_*" ...

Yet another possible improvement is to describe the deselect pattern:

       --trace "virtio_*" --trace "-virtio_mem*"

> +
> +When patterns are used frequently it is more convenient to store them in a
> +file to avoid long command-line options::
>  
>      $ echo "memory_region_ops_*" >/tmp/events
> +    $ echo "kvm_*" >>/tmp/events

Ditto:

       $ echo "-kvm_irqchip_*" >> /tmp/events

>      $ qemu --trace events=/tmp/events ...
>  
>  Trace events
> 

Probably better in a different patch, so for this one:
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>