rtla/osnoise: Track IPIs —— 把跨 CPU 中断干扰从 IRQ 计数中拆出来

+static void account_ipi(struct osnoise_tool *tool, unsigned long long dst_cpu)
+{
+	struct osnoise_top_cpu *cpu_data;
+	struct osnoise_top_data *data;
+	unsigned long long inc = 1;
+
+	data = tool->data;
+	cpu_data = &data->cpu_data[dst_cpu];
+
+	update_sum(&cpu_data->ipi_count, &inc);
+}
+
+/*
+ * osnoise_ipi_cpu_handler - this is the handler for single CPU IPI events.
+ */
+static int
+osnoise_ipi_cpu_handler(struct trace_seq *s, struct tep_record *record,
+		     struct tep_event *event, void *context)
+{
+	struct osnoise_tool *tool;
+	struct osnoise_params *params;
+	unsigned long long dst_cpu;
+	struct trace_instance *trace = context;
+
+	tool = container_of(trace, struct osnoise_tool, trace);
+	params = to_osnoise_params(tool->params);
+
+	tep_get_field_val(s, event, "cpu", record, &dst_cpu, 1);
+
+	if (CPU_ISSET(dst_cpu, &params->common.monitored_cpus))
+		account_ipi(tool, dst_cpu);
+
+	return 0;
+}

+int osnoise_init_ipi_filters(struct osnoise_tool *tool,
+			    struct common_params *params,
+			    bool *filters_enabled)
+{
+	char filter[MAX_PATH];
+	int retval;
+	/*
+	 * If tracing on a subset of possible CPUs, leverage the kernel filtering
+	 * infrastructure to only generate events on traced CPUs.
+	 * Older kernels (pre v6.6) may have the IPI events but not the ability
+	 * to filter them, so allow that to fail gracefully.
+	 */
+
+	snprintf(filter, ARRAY_SIZE(filter), "cpu & CPUS{%s}\n", params->cpus);
+	retval = tracefs_event_file_write(tool->trace.inst,
+					  "ipi", "ipi_send_cpu", "filter",
+					  filter);
+	if (retval < 0) {
+		debug_msg("Could not set ipi_send_cpu CPU filter\n");
+		*filters_enabled = false;
+		return 0;
+	}
+
+	snprintf(filter, ARRAY_SIZE(filter), "cpumask & CPUS{%s}\n", params->cpus);
+	retval = tracefs_event_file_write(tool->trace.inst,
+					  "ipi", "ipi_send_cpumask", "filter",
+					  filter);
+	if (retval < 0) {
+		/*
+		 * If we managed to set up the previous filter but not
+		 * this one, something's really wrong
+		 */
+		err_msg("Could not set ipi_send_cpumask CPU filter\n");
+		*filters_enabled = false;
+		return -1;
+	}
+
+	*filters_enabled = true;
+	return 0;
+}