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From: Steven Rostedt <rostedt@goodmis.org>
To: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
Cc: linux-trace-devel@vger.kernel.org
Subject: Re: [PATCH v18 10/18] trace-cmd: Store the session tracing ID in the trace.dat file
Date: Fri, 20 Dec 2019 15:04:13 -0500
Message-ID: <20191220150413.5d1c52e5@gandalf.local.home> (raw)
In-Reply-To: <20191213153029.133570-11-tz.stoyanov@gmail.com>

On Fri, 13 Dec 2019 17:30:21 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> The ID of the current tracing session is stored in the trace.dat file.
> A new file option is introduced:
> 	TRACECMD_OPTION_TRACEID
> The data is stored in the file as NULL terminated string:
> 	"\nTraceID: %llu\n"

If the trace ID is just a 64 bit number, why is it stored in the file
as a string?

-- Steve


> A new libtracecmd API is introduced, to get the ID when the trace.dat file is read:
> 	unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  include/trace-cmd/trace-cmd.h |  2 ++
>  lib/trace-cmd/trace-input.c   | 25 +++++++++++++++++++++++++
>  tracecmd/trace-record.c       | 15 +++++++++++++++
>  3 files changed, 42 insertions(+)
> 
> diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
> index ad69313..6cc2913 100644
> --- a/include/trace-cmd/trace-cmd.h
> +++ b/include/trace-cmd/trace-cmd.h
> @@ -86,6 +86,7 @@ enum {
>  	TRACECMD_OPTION_CPUCOUNT,
>  	TRACECMD_OPTION_VERSION,
>  	TRACECMD_OPTION_PROCMAPS,
> +	TRACECMD_OPTION_TRACEID,
>  };
>  
>  enum {
> @@ -128,6 +129,7 @@ int tracecmd_copy_headers(struct tracecmd_input *handle, int fd);
>  void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
>  void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
>  unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
> +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
>  
>  void tracecmd_parse_trace_clock(struct tracecmd_input *handle, char *file, int size);
>  
> diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
> index 91362f3..40d9825 100644
> --- a/lib/trace-cmd/trace-input.c
> +++ b/lib/trace-cmd/trace-input.c
> @@ -79,6 +79,7 @@ struct tracecmd_input {
>  	struct tep_plugin_list	*plugin_list;
>  	struct tracecmd_input	*parent;
>  	unsigned long		flags;
> +	unsigned long long	trace_id;
>  	int			fd;
>  	int			long_size;
>  	int			page_size;
> @@ -2169,6 +2170,15 @@ static void procmap_free(struct pid_addr_maps *maps)
>  	free(maps);
>  }
>  
> +static int trace_traceid_load(struct tracecmd_input *handle, char *buf)
> +{
> +
> +	if (sscanf(buf, "%*s %llu", &handle->trace_id) == 1)
> +		return 0;
> +
> +	return -1;
> +}
> +
>  #define STR_PROCMAP_LINE_MAX	(PATH_MAX+22)
>  static int trace_pid_map_load(struct tracecmd_input *handle, char *buf)
>  {
> @@ -2406,6 +2416,10 @@ static int handle_options(struct tracecmd_input *handle)
>  			if (buf[size-1] == '\0')
>  				trace_pid_map_load(handle, buf);
>  			break;
> +		case TRACECMD_OPTION_TRACEID:
> +			if (buf[size-1] == '\0')
> +				trace_traceid_load(handle, buf);
> +			break;
>  		default:
>  			warning("unknown option %d", option);
>  			break;
> @@ -3507,3 +3521,14 @@ void tracecmd_set_show_data_func(struct tracecmd_input *handle,
>  {
>  	handle->show_data_func = func;
>  }
> +
> +/**
> + * tracecmd_get_traceid - get the trace id of the session
> + * @handle: input handle for the trace.dat file
> + *
> + * Returns the trace id, written in the trace file
> + */
> +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
> +{
> +	return handle->trace_id;
> +}
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index 7089f7b..b65aeb2 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -3714,6 +3714,19 @@ add_pid_maps(struct tracecmd_output *handle, struct buffer_instance *instance)
>  	trace_seq_destroy(&s);
>  }
>  
> +static void
> +add_trace_id(struct tracecmd_output *handle, struct buffer_instance *instance)
> +{
> +	char *str = NULL;
> +	int len;
> +
> +	len = asprintf(&str, "\nTraceID: %llu\n", instance->trace_id);
> +	if (len < 1)
> +		return;
> +	tracecmd_add_option(handle, TRACECMD_OPTION_TRACEID, len + 1, str);
> +	free(str);
> +}
> +
>  static void
>  add_buffer_stat(struct tracecmd_output *handle, struct buffer_instance *instance)
>  {
> @@ -3817,6 +3830,8 @@ static void add_options(struct tracecmd_output *handle, struct common_record_con
>  	add_option_hooks(handle);
>  	add_uname(handle);
>  	add_version(handle);
> +	if (!no_top_instance())
> +		add_trace_id(handle, &top_instance);
>  }
>  
>  static void write_guest_file(struct buffer_instance *instance)


  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-13 15:30 [PATCH v18 00/18]Timestamp synchronization of host - guest tracing session Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 01/18] trace-cmd: Implement new lib API: tracecmd_local_events_system() Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 02/18] trace-cmd: Add support for negative time offsets in trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 03/18] trace-cmd: Add implementations of htonll() and ntohll() Tzvetomir Stoyanov (VMware)
2019-12-21  2:34   ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 04/18] trace-cmd: Add new library APIs for ftrace instances Tzvetomir Stoyanov (VMware)
2019-12-21  3:03   ` Steven Rostedt
2020-01-06 14:47     ` Tzvetomir Stoyanov
2019-12-13 15:30 ` [PATCH v18 05/18] trace-cmd: Add new library API for local CPU count Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 06/18] trace-cmd: Add new library API for reading ftrace buffers Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 07/18] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 08/18] trace-cmd: Implement new API tracecmd_add_option_v() Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 09/18] trace-cmd: Add new API to generate a unique ID of the tracing session Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 10/18] trace-cmd: Store the session tracing ID in the trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-20 20:04   ` Steven Rostedt [this message]
2020-01-06 14:33     ` Tzvetomir Stoyanov
2019-12-13 15:30 ` [PATCH v18 11/18] trace-cmd: Exchange tracing IDs between host and guest Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 12/18] trace-cmd: Implement new option in trace.dat file: TRACECMD_OPTION_TIME_SHIFT Tzvetomir Stoyanov (VMware)
2019-12-21  3:19   ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 13/18] trace-cmd: Add guest information in host's trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-20 20:52   ` Steven Rostedt
2020-01-06 14:43     ` Tzvetomir Stoyanov
2020-01-06 14:55       ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 14/18] trace-cmd: Add host trace clock as guest trace argument Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 15/18] trace-cmd: Refactor few trace-cmd internal functions Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 16/18] trace-cmd: Basic infrastructure for host - guest timestamp synchronization Tzvetomir Stoyanov (VMware)
2019-12-21  4:48   ` Steven Rostedt
2020-01-31  9:53     ` Tzvetomir Stoyanov
2020-01-31 14:49       ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 17/18] trace-cmd: [POC] PTP-like algorithm " Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 18/18] trace-cmd: Debug scripts for " Tzvetomir Stoyanov (VMware)

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