From: Daniel Bristot de Oliveira bristot@kernel.org
mainline inclusion from mainline-v5.16-rc1 commit 2fac8d6486d5c34e2ec7028580142b8209da3f92 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I4G64B CVE: NA
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Currently, the user can start only one instance of timerlat/osnoise tracers and the tracers cannot run in parallel.
As starting point to add more flexibility, let's allow the same tracer to run on different trace instances. The workload will start when the first trace_array (instance) is registered and stop when the last instance is unregistered.
So, while this patch allows the same tracer to run in multiple instances (e.g., two instances running osnoise), it still does not allow instances of timerlat and osnoise in parallel (e.g., one timerlat and osnoise). That is because the osnoise: events have different behavior depending on which tracer is enabled (osnoise or timerlat). Enabling the parallel usage of these two tracers is in my TODO list.
Link: https://lkml.kernel.org/r/38c8f14b613492a4f3f938d9d3bf0b063b72f0f0.163570289...
Cc: Ingo Molnar mingo@redhat.com Cc: Tom Zanussi zanussi@kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Juri Lelli juri.lelli@redhat.com Cc: Clark Williams williams@redhat.com Cc: John Kacur jkacur@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Daniel Bristot de Oliveira bristot@kernel.org Cc: linux-rt-users@vger.kernel.org Cc: linux-trace-devel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira bristot@kernel.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Wang ShaoBo bobo.shaobowang@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- kernel/trace/trace_osnoise.c | 101 +++++++++++++++++++++++++++-------- 1 file changed, 78 insertions(+), 23 deletions(-)
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 4881861a66d7..b949631bc843 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -64,6 +64,24 @@ static bool osnoise_has_registered_instances(void) list); }
+/* + * osnoise_instance_registered - check if a tr is already registered + */ +static int osnoise_instance_registered(struct trace_array *tr) +{ + struct osnoise_instance *inst; + int found = 0; + + rcu_read_lock(); + list_for_each_entry_rcu(inst, &osnoise_instances, list) { + if (inst->tr == tr) + found = 1; + } + rcu_read_unlock(); + + return found; +} + /* * osnoise_register_instance - register a new trace instance * @@ -2079,6 +2097,16 @@ static int osnoise_workload_start(void) { int retval;
+ /* + * Instances need to be registered after calling workload + * start. Hence, if there is already an instance, the + * workload was already registered. Otherwise, this + * code is on the way to register the first instance, + * and the workload will start. + */ + if (osnoise_has_registered_instances()) + return 0; + osn_var_reset_all();
retval = osnoise_hook_events(); @@ -2106,6 +2134,13 @@ static int osnoise_workload_start(void) */ static void osnoise_workload_stop(void) { + /* + * Instances need to be unregistered before calling + * stop. Hence, if there is a registered instance, more + * than one instance is running, and the workload will not + * yet stop. Otherwise, this code is on the way to disable + * the last instance, and the workload can stop. + */ if (osnoise_has_registered_instances()) return;
@@ -2127,7 +2162,11 @@ static void osnoise_tracer_start(struct trace_array *tr) { int retval;
- if (osnoise_has_registered_instances()) + /* + * If the instance is already registered, there is no need to + * register it again. + */ + if (osnoise_instance_registered(tr)) return;
retval = osnoise_workload_start(); @@ -2139,18 +2178,17 @@ static void osnoise_tracer_start(struct trace_array *tr)
static void osnoise_tracer_stop(struct trace_array *tr) { - if (!osnoise_has_registered_instances()) - return; - osnoise_unregister_instance(tr); osnoise_workload_stop(); }
static int osnoise_tracer_init(struct trace_array *tr) { - - /* Only allow one instance to enable this */ - if (osnoise_has_registered_instances()) + /* + * Only allow osnoise tracer if timerlat tracer is not running + * already. + */ + if (timerlat_enabled()) return -EBUSY;
tr->max_latency = 0; @@ -2179,45 +2217,55 @@ static void timerlat_tracer_start(struct trace_array *tr) { int retval;
- if (osnoise_has_registered_instances()) + /* + * If the instance is already registered, there is no need to + * register it again. + */ + if (osnoise_instance_registered(tr)) return;
- osnoise_data.timerlat_tracer = 1; - retval = osnoise_workload_start(); if (retval) - goto out_err; + pr_err(BANNER "Error starting timerlat tracer\n");
osnoise_register_instance(tr);
return; -out_err: - pr_err(BANNER "Error starting timerlat tracer\n"); }
static void timerlat_tracer_stop(struct trace_array *tr) { int cpu;
- if (!osnoise_has_registered_instances()) - return; - - for_each_online_cpu(cpu) - per_cpu(per_cpu_osnoise_var, cpu).sampling = 0; + osnoise_unregister_instance(tr);
- osnoise_tracer_stop(tr); + /* + * Instruct the threads to stop only if this is the last instance. + */ + if (!osnoise_has_registered_instances()) { + for_each_online_cpu(cpu) + per_cpu(per_cpu_osnoise_var, cpu).sampling = 0; + }
- osnoise_data.timerlat_tracer = 0; + osnoise_workload_stop(); }
static int timerlat_tracer_init(struct trace_array *tr) { - /* Only allow one instance to enable this */ - if (osnoise_has_registered_instances()) + /* + * Only allow timerlat tracer if osnoise tracer is not running already. + */ + if (osnoise_has_registered_instances() && !osnoise_data.timerlat_tracer) return -EBUSY;
- tr->max_latency = 0; + /* + * If this is the first instance, set timerlat_tracer to block + * osnoise tracer start. + */ + if (!osnoise_has_registered_instances()) + osnoise_data.timerlat_tracer = 1;
+ tr->max_latency = 0; timerlat_tracer_start(tr);
return 0; @@ -2226,6 +2274,13 @@ static int timerlat_tracer_init(struct trace_array *tr) static void timerlat_tracer_reset(struct trace_array *tr) { timerlat_tracer_stop(tr); + + /* + * If this is the last instance, reset timerlat_tracer allowing + * osnoise to be started. + */ + if (!osnoise_has_registered_instances()) + osnoise_data.timerlat_tracer = 0; }
static struct tracer timerlat_tracer __read_mostly = {