Commit 3035cb6c authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf machine: Factor out machine__idle_thread() 



Factor out machine__idle_thread() so it can be re-used for guest machines.

A thread is needed to find executable code, even for the guest kernel. To
avoid possible future pid number conflicts, the idle thread can be used.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Acked-by: default avatarAndi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210218095801.19576-7-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent fcda5ff7

tools/perf/util/machine.c

+18 −0
Original line number Diff line number Diff line
@@ -598,6 +598,24 @@ struct thread *machine__find_thread(struct machine *machine, pid_t pid, 
	return th;

}



/*

 * Threads are identified by pid and tid, and the idle task has pid == tid == 0.

 * So here a single thread is created for that, but actually there is a separate

 * idle task per cpu, so there should be one 'struct thread' per cpu, but there

 * is only 1. That causes problems for some tools, requiring workarounds. For

 * example get_idle_thread() in builtin-sched.c, or thread_stack__per_cpu().

 */

struct thread *machine__idle_thread(struct machine *machine)

{

	struct thread *thread = machine__findnew_thread(machine, 0, 0);



	if (!thread || thread__set_comm(thread, "swapper", 0) ||

	    thread__set_namespaces(thread, 0, NULL))

		pr_err("problem inserting idle task for machine pid %d\n", machine->pid);



	return thread;

}



struct comm *machine__thread_exec_comm(struct machine *machine,

				       struct thread *thread)

{

tools/perf/util/machine.h

+1 −0
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ u8 machine__addr_cpumode(struct machine *machine, u8 cpumode, u64 addr); 


struct thread *machine__find_thread(struct machine *machine, pid_t pid,

				    pid_t tid);

struct thread *machine__idle_thread(struct machine *machine);

struct comm *machine__thread_exec_comm(struct machine *machine,

				       struct thread *thread);

tools/perf/util/session.c

+3 −22
Original line number Diff line number Diff line
@@ -1789,32 +1789,13 @@ struct thread *perf_session__findnew(struct perf_session *session, pid_t pid) 
	return machine__findnew_thread(&session->machines.host, -1, pid);

}



/*

 * Threads are identified by pid and tid, and the idle task has pid == tid == 0.

 * So here a single thread is created for that, but actually there is a separate

 * idle task per cpu, so there should be one 'struct thread' per cpu, but there

 * is only 1. That causes problems for some tools, requiring workarounds. For

 * example get_idle_thread() in builtin-sched.c, or thread_stack__per_cpu().

 */

int perf_session__register_idle_thread(struct perf_session *session)

{

	struct thread *thread;

	int err = 0;



	thread = machine__findnew_thread(&session->machines.host, 0, 0);

	if (thread == NULL || thread__set_comm(thread, "swapper", 0)) {

		pr_err("problem inserting idle task.\n");

		err = -1;

	}

	struct thread *thread = machine__idle_thread(&session->machines.host);



	if (thread == NULL || thread__set_namespaces(thread, 0, NULL)) {

		pr_err("problem inserting idle task.\n");

		err = -1;

	}



	/* machine__findnew_thread() got the thread, so put it */

	/* machine__idle_thread() got the thread, so put it */

	thread__put(thread);

	return err;

	return thread ? 0 : -1;

}



static void