Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
trace/osnoise: Support hotplug operations
Enable and disable osnoise/timerlat thread during on CPU hotplug online
and offline operations respectivelly.
Link: https://lore.kernel.org/linux-doc/20210621134636.5b332226@oasis.local.home/
Link: https://lkml.kernel.org/r/39f98590b3caeb3c32f09526214058efe0e9272a.1624372313.git.bristot@redhat.com
Cc: Phil Auld <pauld@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Kate Carcia <kcarcia@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Clark Willaims <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
authored by
Daniel Bristot de Oliveira
and committed by
Steven Rostedt (VMware)
c8895e27
ba998f7d
+135
-30
+135
-30
kernel/trace/trace_osnoise.c
+135
-30
kernel/trace/trace_osnoise.c
···
1416
1416
#endif /* CONFIG_TIMERLAT_TRACER */
1417
1417
1418
1418
/*
1419
-
* stop_per_cpu_kthread - stop per-cpu threads
1419
+
* stop_kthread - stop a workload thread
1420
+
*/
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+
static void stop_kthread(unsigned int cpu)
1422
+
{
1423
+
struct task_struct *kthread;
1424
+
1425
+
kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
1426
+
if (kthread)
1427
+
kthread_stop(kthread);
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+
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
1429
+
}
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+
1431
+
/*
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+
* stop_per_cpu_kthread - Stop per-cpu threads
1420
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*
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* Stop the osnoise sampling htread. Use this on unload and at system
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* shutdown.
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*/
1424
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static void stop_per_cpu_kthreads(void)
1425
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{
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-
struct task_struct *kthread;
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int cpu;
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1440
1429
-
for_each_online_cpu(cpu) {
1430
-
kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
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-
if (kthread)
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-
kthread_stop(kthread);
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-
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
1441
+
get_online_cpus();
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+
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+
for_each_online_cpu(cpu)
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+
stop_kthread(cpu);
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+
1446
+
put_online_cpus();
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+
}
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+
1449
+
/*
1450
+
* start_kthread - Start a workload tread
1451
+
*/
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+
static int start_kthread(unsigned int cpu)
1453
+
{
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+
struct task_struct *kthread;
1455
+
void *main = osnoise_main;
1456
+
char comm[24];
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+
1458
+
#ifdef CONFIG_TIMERLAT_TRACER
1459
+
if (osnoise_data.timerlat_tracer) {
1460
+
snprintf(comm, 24, "timerlat/%d", cpu);
1461
+
main = timerlat_main;
1462
+
} else {
1463
+
snprintf(comm, 24, "osnoise/%d", cpu);
1434
1464
}
1465
+
#else
1466
+
snprintf(comm, 24, "osnoise/%d", cpu);
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+
#endif
1468
+
kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
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+
1470
+
if (IS_ERR(kthread)) {
1471
+
pr_err(BANNER "could not start sampling thread\n");
1472
+
stop_per_cpu_kthreads();
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+
return -ENOMEM;
1474
+
}
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+
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+
per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
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+
wake_up_process(kthread);
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+
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+
return 0;
1435
1480
}
1436
1481
1437
1482
/*
···
1488
1443
static int start_per_cpu_kthreads(struct trace_array *tr)
1489
1444
{
1490
1445
struct cpumask *current_mask = &save_cpumask;
1491
-
struct task_struct *kthread;
1492
-
char comm[24];
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-
void *main = osnoise_main;
1446
+
int retval;
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1447
int cpu;
1495
1448
1496
1449
get_online_cpus();
···
1500
1457
* And the CPU is online.
1501
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*/
1502
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cpumask_and(current_mask, cpu_online_mask, current_mask);
1503
-
put_online_cpus();
1504
1460
1505
-
for_each_online_cpu(cpu)
1461
+
for_each_possible_cpu(cpu)
1506
1462
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
1507
1463
1508
1464
for_each_cpu(cpu, current_mask) {
1509
-
#ifdef CONFIG_TIMERLAT_TRACER
1510
-
if (osnoise_data.timerlat_tracer) {
1511
-
snprintf(comm, 24, "timerlat/%d", cpu);
1512
-
main = timerlat_main;
1513
-
} else {
1514
-
snprintf(comm, 24, "osnoise/%d", cpu);
1515
-
}
1516
-
#else
1517
-
snprintf(comm, 24, "osnoise/%d", cpu);
1518
-
#endif
1519
-
kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
1520
-
1521
-
if (IS_ERR(kthread)) {
1522
-
pr_err(BANNER "could not start sampling thread\n");
1465
+
retval = start_kthread(cpu);
1466
+
if (retval) {
1523
1467
stop_per_cpu_kthreads();
1524
-
return -ENOMEM;
1468
+
return retval;
1525
1469
}
1526
-
1527
-
per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
1528
-
wake_up_process(kthread);
1529
1470
}
1471
+
1472
+
put_online_cpus();
1530
1473
1531
1474
return 0;
1532
1475
}
1476
+
1477
+
#ifdef CONFIG_HOTPLUG_CPU
1478
+
static void osnoise_hotplug_workfn(struct work_struct *dummy)
1479
+
{
1480
+
struct trace_array *tr = osnoise_trace;
1481
+
unsigned int cpu = smp_processor_id();
1482
+
1483
+
1484
+
mutex_lock(&trace_types_lock);
1485
+
1486
+
if (!osnoise_busy)
1487
+
goto out_unlock_trace;
1488
+
1489
+
mutex_lock(&interface_lock);
1490
+
get_online_cpus();
1491
+
1492
+
if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
1493
+
goto out_unlock;
1494
+
1495
+
if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
1496
+
goto out_unlock;
1497
+
1498
+
start_kthread(cpu);
1499
+
1500
+
out_unlock:
1501
+
put_online_cpus();
1502
+
mutex_unlock(&interface_lock);
1503
+
out_unlock_trace:
1504
+
mutex_unlock(&trace_types_lock);
1505
+
}
1506
+
1507
+
static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn);
1508
+
1509
+
/*
1510
+
* osnoise_cpu_init - CPU hotplug online callback function
1511
+
*/
1512
+
static int osnoise_cpu_init(unsigned int cpu)
1513
+
{
1514
+
schedule_work_on(cpu, &osnoise_hotplug_work);
1515
+
return 0;
1516
+
}
1517
+
1518
+
/*
1519
+
* osnoise_cpu_die - CPU hotplug offline callback function
1520
+
*/
1521
+
static int osnoise_cpu_die(unsigned int cpu)
1522
+
{
1523
+
stop_kthread(cpu);
1524
+
return 0;
1525
+
}
1526
+
1527
+
static void osnoise_init_hotplug_support(void)
1528
+
{
1529
+
int ret;
1530
+
1531
+
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "trace/osnoise:online",
1532
+
osnoise_cpu_init, osnoise_cpu_die);
1533
+
if (ret < 0)
1534
+
pr_warn(BANNER "Error to init cpu hotplug support\n");
1535
+
1536
+
return;
1537
+
}
1538
+
#else /* CONFIG_HOTPLUG_CPU */
1539
+
static void osnoise_init_hotplug_support(void)
1540
+
{
1541
+
return 0;
1542
+
}
1543
+
#endif /* CONFIG_HOTPLUG_CPU */
1533
1544
1534
1545
/*
1535
1546
* osnoise_cpus_read - Read function for reading the "cpus" file
···
1680
1583
osnoise_tracer_stop(tr);
1681
1584
1682
1585
mutex_lock(&interface_lock);
1586
+
/*
1587
+
* osnoise_cpumask is read by CPU hotplug operations.
1588
+
*/
1589
+
get_online_cpus();
1590
+
1683
1591
cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new);
1592
+
1593
+
put_online_cpus();
1684
1594
mutex_unlock(&interface_lock);
1685
1595
1686
1596
if (running)
···
2044
1940
return ret;
2045
1941
}
2046
1942
#endif
1943
+
osnoise_init_hotplug_support();
2047
1944
2048
1945
init_tracefs();
2049
1946