static struct dentry *hwlat_sample_width; /* sample width us */
static struct dentry *hwlat_sample_window; /* sample window us */
+static struct dentry *hwlat_thread_mode; /* hwlat thread mode */
+
+enum {
+ MODE_NONE = 0,
+ MODE_ROUND_ROBIN,
+ MODE_MAX
+};
+static char *thread_mode_str[] = { "none", "round-robin" };
/* Save the previous tracing_thresh value */
static unsigned long save_tracing_thresh;
u64 sample_window; /* total sampling window (on+off) */
u64 sample_width; /* active sampling portion of window */
+ int thread_mode; /* thread mode */
+
} hwlat_data = {
.sample_window = DEFAULT_SAMPLE_WINDOW,
.sample_width = DEFAULT_SAMPLE_WIDTH,
+ .thread_mode = MODE_ROUND_ROBIN
};
+static bool hwlat_busy;
+
static void trace_hwlat_sample(struct hwlat_sample *sample)
{
struct trace_array *tr = hwlat_trace;
while (!kthread_should_stop()) {
- move_to_next_cpu();
+ if (hwlat_data.thread_mode == MODE_ROUND_ROBIN)
+ move_to_next_cpu();
local_irq_disable();
get_sample();
return 0;
}
-/**
+/*
* start_kthread - Kick off the hardware latency sampling/detector kthread
*
* This starts the kernel thread that will sit and sample the CPU timestamp
if (hwlat_kthread)
return 0;
- /* Just pick the first CPU on first iteration */
- get_online_cpus();
- cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
- put_online_cpus();
- next_cpu = cpumask_first(current_mask);
kthread = kthread_create(kthread_fn, NULL, "hwlatd");
if (IS_ERR(kthread)) {
return -ENOMEM;
}
- cpumask_clear(current_mask);
- cpumask_set_cpu(next_cpu, current_mask);
+
+ /* Just pick the first CPU on first iteration */
+ get_online_cpus();
+ cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
+ put_online_cpus();
+
+ if (hwlat_data.thread_mode == MODE_ROUND_ROBIN) {
+ next_cpu = cpumask_first(current_mask);
+ cpumask_clear(current_mask);
+ cpumask_set_cpu(next_cpu, current_mask);
+
+ }
+
sched_setaffinity(kthread->pid, current_mask);
hwlat_kthread = kthread;
return 0;
}
-/**
+/*
* stop_kthread - Inform the hardware latency sampling/detector kthread to stop
*
* This kicks the running hardware latency sampling/detector kernel thread and
return cnt;
}
+static void *s_mode_start(struct seq_file *s, loff_t *pos)
+{
+ int mode = *pos;
+
+ mutex_lock(&hwlat_data.lock);
+
+ if (mode >= MODE_MAX)
+ return NULL;
+
+ return pos;
+}
+
+static void *s_mode_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ int mode = ++(*pos);
+
+ if (mode >= MODE_MAX)
+ return NULL;
+
+ return pos;
+}
+
+static int s_mode_show(struct seq_file *s, void *v)
+{
+ loff_t *pos = v;
+ int mode = *pos;
+
+ if (mode == hwlat_data.thread_mode)
+ seq_printf(s, "[%s]", thread_mode_str[mode]);
+ else
+ seq_printf(s, "%s", thread_mode_str[mode]);
+
+ if (mode != MODE_MAX)
+ seq_puts(s, " ");
+
+ return 0;
+}
+
+static void s_mode_stop(struct seq_file *s, void *v)
+{
+ seq_puts(s, "\n");
+ mutex_unlock(&hwlat_data.lock);
+}
+
+static const struct seq_operations thread_mode_seq_ops = {
+ .start = s_mode_start,
+ .next = s_mode_next,
+ .show = s_mode_show,
+ .stop = s_mode_stop
+};
+
+static int hwlat_mode_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &thread_mode_seq_ops);
+};
+
+static void hwlat_tracer_start(struct trace_array *tr);
+static void hwlat_tracer_stop(struct trace_array *tr);
+
+/**
+ * hwlat_mode_write - Write function for "mode" entry
+ * @filp: The active open file structure
+ * @ubuf: The user buffer that contains the value to write
+ * @cnt: The maximum number of bytes to write to "file"
+ * @ppos: The current position in @file
+ *
+ * This function provides a write implementation for the "mode" interface
+ * to the hardware latency detector. hwlatd has different operation modes.
+ * The "none" sets the allowed cpumask for a single hwlatd thread at the
+ * startup and lets the scheduler handle the migration. The default mode is
+ * the "round-robin" one, in which a single hwlatd thread runs, migrating
+ * among the allowed CPUs in a round-robin fashion.
+ */
+static ssize_t hwlat_mode_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct trace_array *tr = hwlat_trace;
+ const char *mode;
+ char buf[64];
+ int ret, i;
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ mode = strstrip(buf);
+
+ ret = -EINVAL;
+
+ /*
+ * trace_types_lock is taken to avoid concurrency on start/stop
+ * and hwlat_busy.
+ */
+ mutex_lock(&trace_types_lock);
+ if (hwlat_busy)
+ hwlat_tracer_stop(tr);
+
+ mutex_lock(&hwlat_data.lock);
+
+ for (i = 0; i < MODE_MAX; i++) {
+ if (strcmp(mode, thread_mode_str[i]) == 0) {
+ hwlat_data.thread_mode = i;
+ ret = cnt;
+ }
+ }
+
+ mutex_unlock(&hwlat_data.lock);
+
+ if (hwlat_busy)
+ hwlat_tracer_start(tr);
+ mutex_unlock(&trace_types_lock);
+
+ *ppos += cnt;
+
+
+
+ return ret;
+}
+
static const struct file_operations width_fops = {
.open = tracing_open_generic,
.read = hwlat_read,
.write = hwlat_window_write,
};
+static const struct file_operations thread_mode_fops = {
+ .open = hwlat_mode_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+ .write = hwlat_mode_write
+};
/**
* init_tracefs - A function to initialize the tracefs interface files
*
if (!hwlat_sample_width)
goto err;
+ hwlat_thread_mode = trace_create_file("mode", 0644,
+ top_dir,
+ NULL,
+ &thread_mode_fops);
+ if (!hwlat_thread_mode)
+ goto err;
+
return 0;
err:
stop_kthread();
}
-static bool hwlat_busy;
-
static int hwlat_tracer_init(struct trace_array *tr)
{
/* Only allow one instance to enable this */
projects / linux-2.6-microblaze.git / commitdiff