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

[Daniel Walker]

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@xxxxxxxxxx>

---
 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);
 

-- 
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