[PATCH -rt 7/8] latency hist: add resetting for all timing options

Daniel Walker
2007-08-28T21:41:27Z

[-- Attachment #1: latency_tracing_histogram_reset.patch --]
[-- Type: text/plain, Size: 7675 bytes --]

I dropped parts of the prior reset method, and added a file called
"reset" into the /proc/latency_hist/ timing directories. It allows
any of the timing options to get their histograms reset.

I also fixed a couple of oddities in the code. Instead of creating a
file for all NR_CPUS , I just used num_possible_cpus() . I also drop
a string which only hold "CPU" and just inserted it where it was used.

Signed-off-by: Daniel Walker <dwalker@mvista.com>

---
include/linux/latency_hist.h | 1
kernel/latency_hist.c | 119 ++++++++++++++++++++++++++++---------------
kernel/latency_trace.c | 13 ----
3 files changed, 80 insertions(+), 53 deletions(-)

Index: linux-2.6.22/include/linux/latency_hist.h
===================================================================
--- linux-2.6.22.orig/include/linux/latency_hist.h
+++ linux-2.6.22/include/linux/latency_hist.h
@@ -23,7 +23,6 @@ enum {

#ifdef CONFIG_LATENCY_HIST
extern void latency_hist(int latency_type, int cpu, unsigned long latency);
-extern void latency_hist_reset(void);
# define latency_hist_flag 1
#else
# define latency_hist(a,b,c) do { (void)(cpu); } while (0)
Index: linux-2.6.22/kernel/latency_hist.c
===================================================================
--- linux-2.6.22.orig/kernel/latency_hist.c
+++ linux-2.6.22/kernel/latency_hist.c
@@ -16,6 +16,7 @@
#include <linux/latency_hist.h>
#include <asm/atomic.h>
#include <asm/div64.h>
+#include <asm/uaccess.h>

typedef struct hist_data_struct {
atomic_t hist_mode; /* 0 log, 1 don't log */
@@ -31,8 +32,6 @@ typedef struct hist_data_struct {
static struct proc_dir_entry * latency_hist_root = NULL;
static char * latency_hist_proc_dir_root = "latency_hist";

-static char * percpu_proc_name = "CPU";
-
#ifdef CONFIG_INTERRUPT_OFF_HIST
static DEFINE_PER_CPU(hist_data_t, interrupt_off_hist);
static char * interrupt_off_hist_proc_dir = "interrupt_off_latency";
@@ -56,7 +55,7 @@ static inline u64 u64_div(u64 x, u64 y)
return x;
}

-void latency_hist(int latency_type, int cpu, unsigned long latency)
+void notrace latency_hist(int latency_type, int cpu, unsigned long latency)
{
hist_data_t * my_hist;

@@ -205,6 +204,69 @@ static struct file_operations latency_hi
.release = seq_release,
};

+static void hist_reset(hist_data_t *hist)
+{
+ atomic_dec(&hist->hist_mode);
+
+ memset(hist->hist_array, 0, sizeof(hist->hist_array));
+ hist->beyond_hist_bound_samples = 0UL;
+ hist->min_lat = 0xFFFFFFFFUL;
+ hist->max_lat = 0UL;
+ hist->total_samples = 0UL;
+ hist->accumulate_lat = 0UL;
+ hist->avg_lat = 0UL;
+
+ atomic_inc(&hist->hist_mode);
+}
+
+ssize_t latency_hist_reset(struct file *file, const char __user *a, size_t size, loff_t *off)
+{
+ int cpu;
+ hist_data_t *hist;
+ struct proc_dir_entry *entry_ptr = PDE(file->f_dentry->d_inode);
+ int latency_type = (int)entry_ptr->data;
+
+ switch (latency_type) {
+
+#ifdef CONFIG_WAKEUP_LATENCY_HIST
+ case WAKEUP_LATENCY:
+ for_each_online_cpu(cpu) {
+ hist = &per_cpu(wakeup_latency_hist, cpu);
+ hist_reset(hist);
+ }
+ break;
+#endif
+
+#ifdef CONFIG_PREEMPT_OFF_HIST
+ case PREEMPT_LATENCY:
+ for_each_online_cpu(cpu) {
+ hist = &per_cpu(preempt_off_hist, cpu);
+ hist_reset(hist);
+ }
+ break;
+#endif
+
+#ifdef CONFIG_INTERRUPT_OFF_HIST
+ case INTERRUPT_LATENCY:
+ for_each_online_cpu(cpu) {
+ hist = &per_cpu(interrupt_off_hist, cpu);
+ hist_reset(hist);
+ }
+ break;
+#endif
+ }
+
+ return size;
+}
+
+static struct file_operations latency_hist_reset_seq_fops = {
+ .write = latency_hist_reset,
+};
+
+static struct proc_dir_entry *interrupt_off_reset;
+static struct proc_dir_entry *preempt_off_reset;
+static struct proc_dir_entry *wakeup_latency_reset;
+
static __init int latency_hist_init(void)
{
struct proc_dir_entry *tmp_parent_proc_dir;
@@ -214,11 +276,10 @@ static __init int latency_hist_init(void

latency_hist_root = proc_mkdir(latency_hist_proc_dir_root, NULL);

-
#ifdef CONFIG_INTERRUPT_OFF_HIST
tmp_parent_proc_dir = proc_mkdir(interrupt_off_hist_proc_dir, latency_hist_root);
- for (i = 0; i < NR_CPUS; i++) {
- len = sprintf(procname, "%s%d", percpu_proc_name, i);
+ for (i = 0; i < num_possible_cpus(); i++) {
+ len = sprintf(procname, "CPU%d", i);
procname[len] = '\0';
entry[INTERRUPT_LATENCY][i] =
create_proc_entry(procname, 0, tmp_parent_proc_dir);
@@ -228,12 +289,15 @@ static __init int latency_hist_init(void
atomic_set(&my_hist->hist_mode,1);
my_hist->min_lat = 0xFFFFFFFFUL;
}
+ interrupt_off_reset = create_proc_entry("reset", 0, tmp_parent_proc_dir);
+ interrupt_off_reset->data = INTERRUPT_LATENCY;
+ interrupt_off_reset->proc_fops = &latency_hist_reset_seq_fops;
#endif

#ifdef CONFIG_PREEMPT_OFF_HIST
tmp_parent_proc_dir = proc_mkdir(preempt_off_hist_proc_dir, latency_hist_root);
- for (i = 0; i < NR_CPUS; i++) {
- len = sprintf(procname, "%s%d", percpu_proc_name, i);
+ for (i = 0; i < num_possible_cpus(); i++) {
+ len = sprintf(procname, "CPU%d", i);
procname[len] = '\0';
entry[PREEMPT_LATENCY][i] =
create_proc_entry(procname, 0, tmp_parent_proc_dir);
@@ -243,12 +307,15 @@ static __init int latency_hist_init(void
atomic_set(&my_hist->hist_mode,1);
my_hist->min_lat = 0xFFFFFFFFUL;
}
+ preempt_off_reset = create_proc_entry("reset", 0, tmp_parent_proc_dir);
+ preempt_off_reset->data = PREEMPT_LATENCY;
+ preempt_off_reset->proc_fops = &latency_hist_reset_seq_fops;
#endif

#ifdef CONFIG_WAKEUP_LATENCY_HIST
tmp_parent_proc_dir = proc_mkdir(wakeup_latency_hist_proc_dir, latency_hist_root);
- for (i = 0; i < NR_CPUS; i++) {
- len = sprintf(procname, "%s%d", percpu_proc_name, i);
+ for (i = 0; i < num_possible_cpus(); i++) {
+ len = sprintf(procname, "CPU%d", i);
procname[len] = '\0';
entry[WAKEUP_LATENCY][i] =
create_proc_entry(procname, 0, tmp_parent_proc_dir);
@@ -258,38 +325,12 @@ static __init int latency_hist_init(void
atomic_set(&my_hist->hist_mode,1);
my_hist->min_lat = 0xFFFFFFFFUL;
}
+ wakeup_latency_reset = create_proc_entry("reset", 0, tmp_parent_proc_dir);
+ wakeup_latency_reset->data = WAKEUP_LATENCY;
+ wakeup_latency_reset->proc_fops = &latency_hist_reset_seq_fops;
#endif
return 0;

}

__initcall(latency_hist_init);
-
-
-#ifdef CONFIG_WAKEUP_LATENCY_HIST
-static void hist_reset(hist_data_t *hist)
-{
- atomic_dec(&hist->hist_mode);
-
- memset(hist->hist_array, 0, sizeof(hist->hist_array));
- hist->beyond_hist_bound_samples = 0UL;
- hist->min_lat = 0xFFFFFFFFUL;
- hist->max_lat = 0UL;
- hist->total_samples = 0UL;
- hist->accumulate_lat = 0UL;
- hist->avg_lat = 0UL;
-
- atomic_inc(&hist->hist_mode);
-}
-
-void latency_hist_reset(void)
-{
- int cpu;
- hist_data_t *hist;
-
- for_each_online_cpu(cpu) {
- hist = &per_cpu(wakeup_latency_hist, cpu);
- hist_reset(hist);
- }
-}
-#endif
Index: linux-2.6.22/kernel/latency_trace.c
===================================================================
--- linux-2.6.22.orig/kernel/latency_trace.c
+++ linux-2.6.22/kernel/latency_trace.c
@@ -2207,19 +2207,6 @@ check_wakeup_timing(struct cpu_trace *tr
if (!report_latency(delta))
goto out;

-#ifdef CONFIG_WAKEUP_LATENCY_HIST
- /*
- * Was preempt_max_latency reset?
- * If so, we reinitialize the latency histograms to keep them in sync.
- *
- * FIXME: Remove the poll and write our own procfs handler, so
- * we can trigger on the write to preempt_max_latency
- */
- if (last_preempt_max_latency > 0 && preempt_max_latency == 0)
- latency_hist_reset();
- last_preempt_max_latency = preempt_max_latency;
-#endif
-
____trace(smp_processor_id(), TRACE_FN, tr, CALLER_ADDR0, parent_eip,
0, 0, 0, *flags);

--