Re: [PATCH 5/6] trace-cmd library man pages: Manage trace session with multiple trace peers.

[Steven Rostedt <rostedt@goodmis.org>]

I'm assuming that you can pair multiple guests with a single host?

That is, can we have:


	bool g1 = false, g2 = false;

	host = tracecmd_open_head("trace.dat");
	tracecmd_init_data(host);
	guest1 = tracecmd_open_head("trace-Guest-1.dat");
	guest2 = tracecmd_open_head("trace-Guest-2.dat");

	guest_id_1 = tracecmd_get_traceid(guest1);
	guest_id_2 = tracecmd_get_traceid(guest1);

	if (!tracecmd_get_guest_cpumap(host, guest_id_1, &name1, &vcount1, &cpu_pids1)
		g1 = !tracecmd_init_data(guest1);

	if (!tracecmd_get_guest_cpumap(host, guest_id_2, &name2, &vcount2, &cpu_pids2)
		g2 = !tracecmd_init_data(guest2);

	if (g1) {
		int i;
		for (i = 0; i < vcount1; i++) {
			printf("Host task id %d maps to guest %s cpu %d\n",
				cpu_pids1[i], name1, i);
		}
		tracecmd_unpair_peer(guest1);
	}

	if (g2) {
		int i;
		for (i = 0; i < vcount2; i++) {
			printf("Host task id %d maps to guest %s cpu %d\n",
				cpu_pids2[i], name2, i);
		}
		tracecmd_unpair_peer(guest2);
	}

And use something like the above for the example?

-- Steve


On Wed, 23 Dec 2020 06:34:28 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> +EXAMPLE
> +-------
> +[source,c]
> +--
> +#include <trace-cmd.h>
> +...
> +struct tracecmd_input *host = tracecmd_open_head("trace.dat");
> +	if (!host) {
> +		/* Failed to open host trace file */
> +	}
> +	tracecmd_init_data(host);
> +
> +struct tracecmd_input *guest = tracecmd_open_head("trace-Guest.dat");
> +	if (!guest) {
> +		/* Failed to open guest trace file */
> +	}
> +
> +unsigned long long guest_id = tracecmd_get_traceid(guest);
> +int *cpu_pid;
> +char *name;
> +int vcount;
> +
> +	if (!tracecmd_get_guest_cpumap(host, guest_id, &name, &vcount, &cpu_pid)) {
> +		/* The Host and a guest with name was part of the same trace session.
> +		 * Got guest VCPU to host PID mapping.
> +		 */
> +		if (!tracecmd_pair_peer(guest, host)) {
> +			/* Successfully paired host to the guest handler */
> +			tracecmd_init_data(guest);
> +			...
> +			tracecmd_unpair_peer(guest);
> +		}
> +	}
> +
> +...
> +	tracecmd_close(guest);
> +	tracecmd_close(hadle);
> +
> +--