Re: [Qemu-devel] [PATCH 3/5] trace-cmd: Support trace-agent of virtio-trace

[Steven Rostedt]

On Wed, 2012-08-22 at 17:43 +0900, Yoshihiro YUNOMAE wrote:
> Add read path and control path to use trace-agent of virtio-trace.
> When we use trace-agent, trace-cmd will be used as follows:
>       # AGENT_READ_DIR=/tmp/virtio-trace/tracing \
>         AGENT_CTL=/tmp/virtio-trace/agent-ctl-path.in \
>         TRACING_DIR=/tmp/virtio-trace/debugfs/tracing \\

Ha! You used "TRACING_DIR" but patch one introduces TRACE_DIR. Lets
change this to DEBUG_TRACING_DIR instead anyway.

Also, I don't like the generic environment variables. Perhaps
VIRTIO_TRACE_DIR, or AGENT_TRACE_DIR and AGENT_TRACE_CTL. Lets try to
keep the environment namespace sparse.

>         trace-cmd record -e "sched:*"
> Here, AGENT_READ_DIR is the path for a reading directory of virtio-trace,
> AGENT_CTL is a control path of trace-agent, and TRACING_DIR is a debugfs path
> of a guest.
> 
> Signed-off-by: Yoshihiro YUNOMAE <address@hidden>
> ---
> 
>  trace-cmd.h      |    1 +
>  trace-recorder.c |   57 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  trace-util.c     |   18 +++++++++++++++++
>  3 files changed, 75 insertions(+), 1 deletions(-)
> 
> diff --git a/trace-cmd.h b/trace-cmd.h
> index f904dc5..75506ed 100644
> --- a/trace-cmd.h
> +++ b/trace-cmd.h
> @@ -72,6 +72,7 @@ static inline int tracecmd_host_bigendian(void)
>  }
>  
>  char *tracecmd_find_tracing_dir(void);
> +char *guest_agent_tracing_read_dir(void);
>  
>  /* --- Opening and Reading the trace.dat file --- */
>  
> diff --git a/trace-recorder.c b/trace-recorder.c
> index 215affc..3b750e9 100644
> --- a/trace-recorder.c
> +++ b/trace-recorder.c
> @@ -33,6 +33,7 @@
>  #include <unistd.h>
>  #include <ctype.h>
>  #include <errno.h>
> +#include <stdbool.h>
>  
>  #include "trace-cmd.h"
>  
> @@ -43,6 +44,8 @@ struct tracecmd_recorder {
>       int             page_size;
>       int             cpu;
>       int             stop;
> +     int             ctl_fd;
> +     bool            agent_existing;

Thanks for the reminder. I need to convert a lot to use 'bool' instead.

>  };
>  
>  void tracecmd_free_recorder(struct tracecmd_recorder *recorder)
> @@ -59,11 +62,29 @@ void tracecmd_free_recorder(struct tracecmd_recorder 
> *recorder)
>       free(recorder);
>  }
>  
> +static char *use_trace_agent_dir(char *ctl_path,
> +                                     struct tracecmd_recorder *recorder)
> +{
> +     ctl_path = strdup(ctl_path);
> +     if (!ctl_path)
> +             die("malloc");
> +     warning("Use environmental control path: %s\n", ctl_path);

s/Use/Using/

-- Steve

> +
> +     recorder->ctl_fd = open(ctl_path, O_WRONLY);
> +     if (recorder->ctl_fd < 0)
> +             return NULL;
> +
> +     recorder->agent_existing = true;
> +
> +     return guest_agent_tracing_read_dir();
> +}
> +