Re: [PATCH v4 14/20] kernel-shark: Provide merging of multiple data streams

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 18 Nov 2020 16:49:57 +0200
"Yordan Karadzhov (VMware)" <y.karadz@gmail.com> wrote:

> The C API provides loading of the trace data in two different forms.
> The firs one is an array of kshark_entries and is being used by the

  "first one"

> KernelShark GUI. The second is a matrix-like structure that has all
> the fields of the kshark_entry stored in separate arrays, forming the
> columns of the matrix. The second form of the data is used by
> trace-cruncher. In this patch we add methods for merging of several
> data streams into a single data set. Both kshark_entries and matrix
> forms of the data are supported. This patch includes a simple example
> that demonstrate how to open a file that contains multiple buffers.
> Each buffers is loaded into a separate Data stream and those streams
> are merged together.
> 
> Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
> ---
>  examples/CMakeLists.txt    |   4 +
>  examples/multibufferload.c |  60 +++++++++
>  src/libkshark.c            | 255 +++++++++++++++++++++++++++++++++++++
>  src/libkshark.h            |  47 +++++++
>  4 files changed, 366 insertions(+)
>  create mode 100644 examples/multibufferload.c
> 
> diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
> index 8d40e42c..831eee24 100644
> --- a/examples/CMakeLists.txt
> +++ b/examples/CMakeLists.txt
> @@ -8,6 +8,10 @@ message(STATUS "datafilter")
>  add_executable(dfilter          datafilter.c)
>  target_link_libraries(dfilter   kshark)
>  
> +message(STATUS "multibufferload")
> +add_executable(mbload          multibufferload.c)
> +target_link_libraries(mbload   kshark)
> +
>  # message(STATUS "datahisto")
>  # add_executable(dhisto          datahisto.c)
>  # target_link_libraries(dhisto   kshark)
> diff --git a/examples/multibufferload.c b/examples/multibufferload.c
> new file mode 100644
> index 00000000..70b2733a
> --- /dev/null
> +++ b/examples/multibufferload.c
> @@ -0,0 +1,60 @@
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +#include "libkshark.h"
> +#include "libkshark-tepdata.h"
> +
> +const char *default_file = "trace.dat";
> +
> +void put_entry(struct kshark_entry *e)
> +{
> +	char *entry_str = kshark_dump_entry(e);
> +	puts(entry_str);
> +	free(entry_str);
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	struct kshark_context *kshark_ctx;
> +	struct kshark_entry **data = NULL;
> +	ssize_t r, n_rows;
> +	int sd;
> +
> +	/* Create a new kshark session. */
> +	kshark_ctx = NULL;
> +	if (!kshark_instance(&kshark_ctx))
> +		return 1;
> +
> +	/* Open a trace data file produced by trace-cmd. */
> +	if (argc > 1)
> +		sd = kshark_open(kshark_ctx, argv[1]);
> +	else
> +		sd = kshark_open(kshark_ctx, default_file);

I'm confused. It doesn't look like this merges more than one stream.

-- Steve

> +
> +	if (sd < 0) {
> +		kshark_free(kshark_ctx);
> +		return 1;
> +	}
> +
> +	/* Initialize data streams for all buffers in this file. */
> +	kshark_tep_init_all_buffers(kshark_ctx, sd);
> +
> +	/* Load all buffers. */
> +	n_rows = kshark_load_all_entries(kshark_ctx, &data);
> +
> +	/* Print to the screen the first 20 entries. */
> +	for (r = 0; r < 20; ++r)
> +		put_entry(data[r]);
> +
> +	/* Free the memory. */
> +	for (r = 0; r < n_rows; ++r)
> +		free(data[r]);
> +	free(data);
> +
> +	kshark_close_all(kshark_ctx);
> +
> +	/* Close the session. */
> +	kshark_free(kshark_ctx);
> +
> +	return 0;
> +}