On Thu, 29 Jul 2021 08:09:00 +0300
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx> wrote:
> Extended the BUFFER trace option in trace file version 7 with CPU
> flyrecord trace metadata. In the version 6 of the trace file, this metadata
> is located at several places in the file. Part of the metadata is only for
> the top trace instance, thus limiting per-instance configuration. Moving
> all CPU trace related metadata in the BUFFER option simplifies the parsing
> and makes per-instance configuration more flexible. In the new file
> structure, the top instance is treated as any other instances.
> The format of the extended BUFFER option is:
> - offset of the buffer in the trace file
> - name of the buffer
> - trace clock, used in this buffer for events timestamps
> - count of CPUs with trace data
> - array, describing each CPU with trace data:
> - CPU id
> - offset of CPU trace data in the trace file
> - size of the recorded CPU trace data
>
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
> ---
> lib/trace-cmd/trace-output.c | 171 ++++++++++++++++++++++++++---------
> 1 file changed, 127 insertions(+), 44 deletions(-)
>
> diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
> index d60bd456..21555d6d 100644
> --- a/lib/trace-cmd/trace-output.c
> +++ b/lib/trace-cmd/trace-output.c
> @@ -1826,7 +1826,7 @@ int tracecmd_append_options(struct tracecmd_output *handle)
> }
>
> static struct tracecmd_option *
> -add_buffer_option(struct tracecmd_output *handle, const char *name, int cpus)
> +add_buffer_option_v6(struct tracecmd_output *handle, const char *name, int cpus)
> {
> struct tracecmd_option *option;
> char *buf;
> @@ -1876,8 +1876,11 @@ int tracecmd_write_buffer_info(struct tracecmd_output *handle)
> struct tracecmd_option *option;
> struct tracecmd_buffer *buf;
>
> + if (handle->file_version >= 7)
> + return 0;
> +
> list_for_each_entry(buf, &handle->buffers, list) {
> - option = add_buffer_option(handle, buf->name, buf->cpus);
> + option = add_buffer_option_v6(handle, buf->name, buf->cpus);
> if (!option)
> return -1;
> buf->option = option;
> @@ -1938,6 +1941,98 @@ int tracecmd_write_cmdlines(struct tracecmd_output *handle)
> return 0;
> }
>
> +static char *get_clock(struct tracecmd_output *handle)
> +{
> + struct tracefs_instance *inst;
> +
> + if (handle->trace_clock)
> + return handle->trace_clock;
> +
> + /*
> + * If no clock is set on this handle, get the trace clock of
> + * the top instance in the handle's tracing dir
> + */
> + inst = tracefs_instance_alloc(handle->tracing_dir, NULL);
> + if (!inst)
> + return NULL;
> + handle->trace_clock = tracefs_get_clock(inst);
> + tracefs_instance_free(inst);
> + return handle->trace_clock;
> +}
> +
> +__hidden struct tracecmd_option *
> +out_add_buffer_option_v7(struct tracecmd_output *handle, const char *name,
> + unsigned short id, unsigned long long data_offset,
> + int cpus, struct data_file_write *cpu_data)
Why is this hidden, and not static?
I noticed that you are using "out_" as a normal prefix. Is that really
needed?
> +{
> + struct tracecmd_option *option;
> + int i, j = 0, k = 0;
> + int *cpu_ids = NULL;
> + struct iovec *vect;
> + char *clock;
> +
> + if (handle->file_version < 7)
> + return NULL;
> +
> + clock = get_clock(handle);
> +
> + /* Buffer flyrecord option, v7:
Nit, for consistency, use:
/*
* Buffer flyrecord option, v7:
> + * - trace data offset in the file
Is the above the "meta data". If so, perhaps we should call it that.
> + * - buffer name
> + * - buffer clock
> + * - CPU count
> + * - for each CPU:
> + * - CPU id
> + * - CPU trace data offset in the file
> + * - CPU trace data size
> + */
> +
> + /* Buffer latency option, v7:
> + * - trace data offset in the file
Is this the actual latency?
> + * - buffer name
> + * - buffer clock
> + */
> +
> + vect = calloc(5 + (cpus * 3), sizeof(struct iovec));
Comment what these magic numbers are: 5 and 3.
-- Steve
> + if (!vect)
> + return NULL;
> + if (cpus) {
> + cpu_ids = calloc(cpus, sizeof(int));
> + if (!cpu_ids) {
> + free(vect);
> + return NULL;
> + }
> + }
> + vect[j].iov_base = (void *) &data_offset;
> + vect[j++].iov_len = 8;
> + vect[j].iov_base = (void *) name;
> + vect[j++].iov_len = strlen(name) + 1;
> + vect[j].iov_base = (void *) clock;
> + vect[j++].iov_len = strlen(clock) + 1;
> + if (id == TRACECMD_OPTION_BUFFER) {
> + vect[j].iov_base = (void *) &k;
> + vect[j++].iov_len = 4;
> + for (i = 0; i < cpus; i++) {
> + if (!cpu_data[i].file_size)
> + continue;
> + cpu_ids[i] = i;
> + vect[j].iov_base = &cpu_ids[i];
> + vect[j++].iov_len = 4;
> + vect[j].iov_base = &cpu_data[i].data_offset;
> + vect[j++].iov_len = 8;
> + vect[j].iov_base = &cpu_data[i].write_size;
> + vect[j++].iov_len = 8;
> + k++;
> + }
> + }
> +
> + option = tracecmd_add_option_v(handle, id, vect, j);
> + free(vect);
> + free(cpu_ids);
> +
> + return option;
> +}
> +
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