This patch is the core LatencyTOP kernel infrastructure;
it measures latencies in the scheduler and tracks it system
wide and per process
---
fs/proc/base.c | 61 +++++++++
include/linux/latencytop.h | 62 +++++++++
include/linux/sched.h | 6
kernel/Makefile | 1
kernel/fork.c | 1
kernel/latencytop.c | 287 +++++++++++++++++++++++++++++++++++++++++++++
kernel/sched_fair.c | 8 +
lib/Kconfig.debug | 11 +
8 files changed, 436 insertions(+), 1 deletion(-)
Index: linux-2.6.24-rc7/include/linux/latencytop.h
===================================================================
--- /dev/null
+++ linux-2.6.24-rc7/include/linux/latencytop.h
@@ -0,0 +1,62 @@
+/*
+ * latencytop.h: Infrastructure for displaying latency
+ *
+ * (C) Copyright 2008 Intel Corporation
+ * Author: Arjan van de Ven <[EMAIL PROTECTED]>
+ *
+ */
+
+#ifndef _INCLUDE_GUARD_LATENCYTOP_H_
+#define _INCLUDE_GUARD_LATENCYTOP_H_
+
+#ifdef CONFIG_LATENCYTOP
+
+#define LT_ARGUMENTSIZE 24
+#define LT_SAVECOUNT 32
+
+struct latency_entry {
+ char *reason;
+ char argument[LT_ARGUMENTSIZE];
+ int maxtime; /* ignore latencies above this time as
+ "user requested" to deal with select() */
+};
+
+struct latency_record {
+ char *reason;
+ char argument[LT_ARGUMENTSIZE];
+ unsigned int count;
+ unsigned long time;
+ unsigned long max;
+};
+
+
+struct task_struct;
+
+struct latency_entry *set_latency_reason(char *reason,
+ struct latency_entry *entry);
+struct latency_entry *set_latency_reason_user(char *reason,
+ struct latency_entry *entry, unsigned int max);
+struct latency_entry *set_latency_reason_param(char *reason,
+ const char *param, struct latency_entry *entry);
+void restore_latency_reason(struct latency_entry *entry);
+void account_scheduler_latency(struct task_struct *task, int usecs, int inter);
+
+void clear_all_latency_tracing(struct task_struct *p);
+#else
+struct latency_entry {};
+static inline struct latency_entry *set_latency_reason(char *reason,
+ struct latency_entry *entry) { return NULL; }
+static inline struct latency_entry *set_latency_reason_user(char *reason,
+ struct latency_entry *entry, unsigned int max)
+ { return NULL; }
+static inline struct latency_entry *set_latency_reason_param(char *reason,
+ const char *param, struct latency_entry *entry)
+ { return NULL; }
+static inline void restore_latency_reason(struct latency_entry *entry) { }
+static inline void account_scheduler_latency(struct task_struct *task,
+ int usecs, int inter) {};
+static inline void clear_all_latency_tracing(struct task_struct *p) {};
+
+#endif
+
+#endif
Index: linux-2.6.24-rc7/include/linux/sched.h
===================================================================
--- linux-2.6.24-rc7.orig/include/linux/sched.h
+++ linux-2.6.24-rc7/include/linux/sched.h
@@ -88,6 +88,7 @@ struct sched_param {
#include <linux/hrtimer.h>
#include <linux/task_io_accounting.h>
#include <linux/kobject.h>
+#include <linux/latencytop.h>
#include <asm/processor.h>
@@ -1178,6 +1179,11 @@ struct task_struct {
int make_it_fail;
#endif
struct prop_local_single dirties;
+#ifdef CONFIG_LATENCYTOP
+ struct latency_entry latency_reason;
+ int latency_record_count;
+ struct latency_record latency_record[LT_SAVECOUNT];
+#endif
};
/*
Index: linux-2.6.24-rc7/kernel/fork.c
===================================================================
--- linux-2.6.24-rc7.orig/kernel/fork.c
+++ linux-2.6.24-rc7/kernel/fork.c
@@ -1196,6 +1196,7 @@ static struct task_struct *copy_process(
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
+ clear_all_latency_tracing(p);
/* Our parent execution domain becomes current domain
These must match for thread signalling to apply */
Index: linux-2.6.24-rc7/kernel/latencytop.c
===================================================================
--- /dev/null
+++ linux-2.6.24-rc7/kernel/latencytop.c
@@ -0,0 +1,287 @@
+/*
+ * latencytop.c: Latency display infrastructure
+ *
+ * (C) Copyright 2008 Intel Corporation
+ * Author: Arjan van de Ven <[EMAIL PROTECTED]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#include <linux/latencytop.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/sched.h>
+#include <linux/kallsyms.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+
+static DEFINE_SPINLOCK(latency_lock);
+
+#define MAXLR 128
+static struct latency_record latency_record[MAXLR];
+
+struct latency_entry *set_latency_reason(char *reason,
+ struct latency_entry *entry)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&latency_lock, flags);
+
+ *entry = current->latency_reason;
+ if (current->latency_reason.reason) {
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return entry;
+ }
+
+ current->latency_reason.reason = reason;
+ current->latency_reason.argument[0] = 0;
+ current->latency_reason.maxtime = 0;
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return entry;
+}
+
+struct latency_entry *set_latency_reason_user(char *reason,
+ struct latency_entry *entry, unsigned int max)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&latency_lock, flags);
+
+ *entry = current->latency_reason;
+ if (current->latency_reason.reason) {
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return entry;
+ }
+
+ current->latency_reason.reason = reason;
+ current->latency_reason.argument[0] = 0;
+ current->latency_reason.maxtime = max;
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return entry;
+}
+
+struct latency_entry *set_latency_reason_param(char *reason,
+ char const *param, struct latency_entry *entry)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&latency_lock, flags);
+
+ *entry = current->latency_reason;
+ if (current->latency_reason.reason) {
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return entry;
+ }
+
+ current->latency_reason.reason = reason;
+ current->latency_reason.maxtime = 0;
+ if (param)
+ strncpy(current->latency_reason.argument, param, 23);
+ else
+ current->latency_reason.argument[0] = 0;
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return entry;
+}
+EXPORT_SYMBOL(set_latency_reason);
+
+void restore_latency_reason(struct latency_entry *entry)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&latency_lock, flags);
+ current->latency_reason = *entry;
+ spin_unlock_irqrestore(&latency_lock, flags);
+}
+EXPORT_SYMBOL(restore_latency_reason);
+
+void clear_all_latency_tracing(struct task_struct *p)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&latency_lock, flags);
+ memset(&p->latency_reason, 0, sizeof(p->latency_reason));
+ memset(&p->latency_record, 0, sizeof(p->latency_record));
+ p->latency_record_count = 0;
+ spin_unlock_irqrestore(&latency_lock, flags);
+}
+
+static void clear_global_latency_tracing(void)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&latency_lock, flags);
+ memset(&latency_record, 0, sizeof(latency_record));
+ spin_unlock_irqrestore(&latency_lock, flags);
+}
+
+static void __sched
+account_global_scheduler_latency(struct task_struct *tsk, int usecs)
+{
+ int i;
+ int firstnonnull = MAXLR + 1;
+
+ if (!tsk->latency_reason.reason)
+ return;
+
+ /* skip kernel threads for now */
+ if (!tsk->mm)
+ return;
+
+ for (i = 0; i < MAXLR; i++) {
+ /* nothing stored */
+ if (!latency_record[i].reason) {
+ if (firstnonnull > i)
+ firstnonnull = i;
+ continue;
+ }
+ /* mismatch on the reason */
+ if (strcmp(latency_record[i].reason,
+ tsk->latency_reason.reason))
+ continue;
+ /* mismatch on the argument */
+ if (strcmp(latency_record[i].argument,
+ tsk->latency_reason.argument))
+ continue;
+ latency_record[i].count++;
+ latency_record[i].time += usecs;
+ if (usecs > latency_record[i].max)
+ latency_record[i].max = usecs;
+ return;
+ }
+
+ i = firstnonnull;
+ if (i >= MAXLR - 1)
+ return;
+
+ /* allocted a new one */
+ latency_record[i].reason = tsk->latency_reason.reason;
+ strcpy(latency_record[i].argument, tsk->latency_reason.argument);
+ latency_record[i].count = 1;
+ latency_record[i].time = usecs;
+ latency_record[i].max = usecs;
+}
+
+void __sched account_scheduler_latency(struct task_struct *tsk,
+ int usecs, int inter)
+{
+ int i;
+ unsigned long flags;
+
+ /* long interruptible waits are generally user requested.. */
+ if (inter && usecs > 5000)
+ return;
+
+ /* no reason for the latency... bail for now. Later we'll
+ * store a backtrace item instead
+ */
+ if (!tsk->latency_reason.reason && tsk->latency_record_count > 15)
+ return;
+
+ /* if we have a maxtime set (as is the case for select and such),
+ and we're waiting longer than that, assume it's a user requested
+ delay and don't log it */
+ if (tsk->latency_reason.maxtime &&
+ usecs > tsk->latency_reason.maxtime)
+ return;
+
+ spin_lock_irqsave(&latency_lock, flags);
+ if (!tsk->latency_reason.reason) {
+ static char str[KSYM_NAME_LEN];
+ unsigned long EIPV = get_wchan(tsk);
+ sprint_symbol(str, EIPV);
+ tsk->latency_reason.reason = "Unknown reason";
+ strncpy(tsk->latency_reason.argument, str, 23);
+ }
+
+ account_global_scheduler_latency(tsk, usecs);
+
+ /* check if the reason is already in the table */
+ for (i = 0; i < LT_SAVECOUNT; i++) {
+ /* nothing stored */
+ if (!tsk->latency_record[i].reason)
+ continue;
+ /* mismatch on the reason */
+ if (strcmp(tsk->latency_record[i].reason,
+ tsk->latency_reason.reason))
+ continue;
+ /* mismatch on the argument */
+ if (strcmp(tsk->latency_record[i].argument,
+ tsk->latency_reason.argument))
+ continue;
+ tsk->latency_record[i].count++;
+ tsk->latency_record[i].time += usecs;
+ if (usecs > tsk->latency_record[i].max)
+ tsk->latency_record[i].max = usecs;
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return;
+ }
+ /* short term hack; if we're > 32 we stop; future we recycle */
+ tsk->latency_record_count++;
+ if (tsk->latency_record_count >= LT_SAVECOUNT) {
+ spin_unlock_irqrestore(&latency_lock, flags);
+ return;
+ }
+ /* allocted a new one */
+ i = tsk->latency_record_count;
+ tsk->latency_record[i].reason = tsk->latency_reason.reason;
+ strcpy(tsk->latency_record[i].argument, tsk->latency_reason.argument);
+ tsk->latency_record[i].count = 1;
+ tsk->latency_record[i].time = usecs;
+ tsk->latency_record[i].max = usecs;
+ spin_unlock_irqrestore(&latency_lock, flags);
+
+}
+
+
+
+static int lstats_show(struct seq_file *m, void *v)
+{
+ int i;
+ seq_puts(m, "Latency Top version : v0.1\n");
+
+ for (i = 0; i < MAXLR; i++) {
+ if (latency_record[i].reason)
+ seq_printf(m, "%i %li %li %s (%s)\n",
+ latency_record[i].count,
+ latency_record[i].time,
+ latency_record[i].max,
+ latency_record[i].reason,
+ latency_record[i].argument);
+
+ }
+ return 0;
+}
+
+static ssize_t lstats_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *offs)
+{
+ clear_global_latency_tracing();
+ return count;
+}
+
+static int lstats_open(struct inode *inode, struct file *filp)
+{
+ return single_open(filp, lstats_show, NULL);
+}
+
+static struct file_operations lstats_fops = {
+ .open = lstats_open,
+ .read = seq_read,
+ .write = lstats_write,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init init_lstats_procfs(void)
+{
+ struct proc_dir_entry *pe;
+
+ pe = create_proc_entry("latency_stats", 0644, NULL);
+ if (!pe)
+ return -ENOMEM;
+
+ pe->proc_fops = &lstats_fops;
+
+ return 0;
+}
+__initcall(init_lstats_procfs);
Index: linux-2.6.24-rc7/kernel/Makefile
===================================================================
--- linux-2.6.24-rc7.orig/kernel/Makefile
+++ linux-2.6.24-rc7/kernel/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
obj-$(CONFIG_MARKERS) += marker.o
+obj-$(CONFIG_LATENCYTOP) += latencytop.o
ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <[EMAIL PROTECTED]>, the -fno-omit-frame-pointer is
Index: linux-2.6.24-rc7/kernel/sched_fair.c
===================================================================
--- linux-2.6.24-rc7.orig/kernel/sched_fair.c
+++ linux-2.6.24-rc7/kernel/sched_fair.c
@@ -20,6 +20,8 @@
* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <[EMAIL PROTECTED]>
*/
+#include <linux/latencytop.h>
+
/*
* Targeted preemption latency for CPU-bound tasks:
* (default: 20ms * (1 + ilog(ncpus)), units: nanoseconds)
@@ -434,6 +436,7 @@ static void enqueue_sleeper(struct cfs_r
#ifdef CONFIG_SCHEDSTATS
if (se->sleep_start) {
u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
+ struct task_struct *tsk = task_of(se);
if ((s64)delta < 0)
delta = 0;
@@ -443,9 +446,12 @@ static void enqueue_sleeper(struct cfs_r
se->sleep_start = 0;
se->sum_sleep_runtime += delta;
+
+ account_scheduler_latency(tsk, delta >> 10, 1);
}
if (se->block_start) {
u64 delta = rq_of(cfs_rq)->clock - se->block_start;
+ struct task_struct *tsk = task_of(se);
if ((s64)delta < 0)
delta = 0;
@@ -462,11 +468,11 @@ static void enqueue_sleeper(struct cfs_r
* time that the task spent sleeping:
*/
if (unlikely(prof_on == SLEEP_PROFILING)) {
- struct task_struct *tsk = task_of(se);
profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
delta >> 20);
}
+ account_scheduler_latency(tsk, delta >> 10, 0);
}
#endif
}
Index: linux-2.6.24-rc7/fs/proc/base.c
===================================================================
--- linux-2.6.24-rc7.orig/fs/proc/base.c
+++ linux-2.6.24-rc7/fs/proc/base.c
@@ -310,6 +310,60 @@ static int proc_pid_schedstat(struct tas
}
#endif
+#ifdef CONFIG_LATENCYTOP
+static int lstats_show_proc(struct seq_file *m, void *v)
+{
+ int i;
+ struct task_struct *task = m->private;
+ seq_puts(m, "Latency Top version : v0.1\n");
+
+ for (i = 0; i < 32; i++) {
+ if (task->latency_record[i].reason)
+ seq_printf(m, "%i %li %li %s (%s)\n",
+ task->latency_record[i].count,
+ task->latency_record[i].time,
+ task->latency_record[i].max,
+ task->latency_record[i].reason,
+ task->latency_record[i].argument);
+
+ }
+ return 0;
+}
+
+static int lstats_open(struct inode *inode, struct file *file)
+{
+ int ret;
+ struct seq_file *m;
+ struct task_struct *task = get_proc_task(inode);
+ ret = single_open(file, lstats_show_proc, NULL);
+ if (!ret) {
+ m = file->private_data;
+ m->private = task;
+ }
+ return ret;
+}
+
+static ssize_t lstats_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *offs)
+{
+ struct seq_file *m;
+ struct task_struct *task;
+ m = file->private_data;
+ task = m->private;
+ clear_all_latency_tracing(task);
+ return count;
+}
+
+static const struct file_operations proc_lstats_operations = {
+ .open = lstats_open,
+ .read = seq_read,
+ .write = lstats_write,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+#endif
+
/* The badness from the OOM killer */
unsigned long badness(struct task_struct *p, unsigned long uptime);
static int proc_oom_score(struct task_struct *task, char *buffer)
@@ -1020,6 +1074,7 @@ static const struct file_operations proc
};
#endif
+
#ifdef CONFIG_SCHED_DEBUG
/*
* Print out various scheduling related per-task fields:
@@ -2230,6 +2285,9 @@ static const struct pid_entry tgid_base_
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, pid_schedstat),
#endif
+#ifdef CONFIG_LATENCYTOP
+ REG("latency", S_IRUGO, lstats),
+#endif
#ifdef CONFIG_PROC_PID_CPUSET
REG("cpuset", S_IRUGO, cpuset),
#endif
@@ -2555,6 +2613,9 @@ static const struct pid_entry tid_base_s
#ifdef CONFIG_SCHEDSTATS
INF("schedstat", S_IRUGO, pid_schedstat),
#endif
+#ifdef CONFIG_LATENCYTOP
+ REG("latency", S_IRUGO, lstats),
+#endif
#ifdef CONFIG_PROC_PID_CPUSET
REG("cpuset", S_IRUGO, cpuset),
#endif
Index: linux-2.6.24-rc7/lib/Kconfig.debug
===================================================================
--- linux-2.6.24-rc7.orig/lib/Kconfig.debug
+++ linux-2.6.24-rc7/lib/Kconfig.debug
@@ -517,4 +517,15 @@ config FAULT_INJECTION_STACKTRACE_FILTER
help
Provide stacktrace filter for fault-injection capabilities
+config LATENCYTOP
+ bool "Latency measuring infrastructure"
+ select FRAME_POINTER if !X86 && !MIPS
+ select KALLSYMS
+ select KALLSYMS_ALL
+ depends on SCHEDSTATS
+ help
+ Enable this option if you want to use the LatencyTOP tool
+ to find out which userspace is blocking on what kernel operations.
+
+
source "samples/Kconfig"
--
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