Attachment 294454 Details for Bug 431651 – LatencyTOP kernel patch

[patch] LatencyTOP kernel patch

latencytop.patch (text/plain), 16.71 KB, created by Joachim Frieben on 2008-02-09 07:13:18 UTC

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Creator: Joachim Frieben

Created: 2008-02-09 07:13:18 UTC

Size: 16.71 KB

patch

obsolete

>From: Arjan van de Ven <arjan@linux.intel.com>
>Subject: [PATCH] LatencyTOP infrastructure patch
>
>This patch is the core LatencyTOP kernel infrastructure;
>it measures latencies in the scheduler and tracks it system
>wide and per process.
>
>Signed-off-by: Ingo Molnar <mingo@elte.hu>
>Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
>
>---
> arch/x86/kernel/stacktrace.c |   27 ++++
> fs/proc/base.c               |   79 ++++++++++++++
> include/linux/latencytop.h   |   44 +++++++
> include/linux/sched.h        |    5 
> include/linux/stacktrace.h   |    3 
> kernel/Makefile              |    1 
> kernel/fork.c                |    1 
> kernel/latencytop.c          |  241 +++++++++++++++++++++++++++++++++++++++++++
> kernel/sched_fair.c          |    8 +
> kernel/sysctl.c              |   10 +
> lib/Kconfig.debug            |   12 ++
> 11 files changed, 430 insertions(+), 1 deletion(-)
>
>Index: linux-2.6.24-rc8/arch/x86/kernel/stacktrace.c
>===================================================================
>--- linux-2.6.24-rc8.orig/arch/x86/kernel/stacktrace.c
>+++ linux-2.6.24-rc8/arch/x86/kernel/stacktrace.c
>@@ -33,6 +33,19 @@ static void save_stack_address(void *dat
> 		trace->entries[trace->nr_entries++] = addr;
> }
> 
>+static void save_stack_address_nosched(void *data, unsigned long addr)
>+{
>+	struct stack_trace *trace = (struct stack_trace *)data;
>+	if (in_sched_functions(addr))
>+		return;
>+	if (trace->skip > 0) {
>+		trace->skip--;
>+		return;
>+	}
>+	if (trace->nr_entries < trace->max_entries)
>+		trace->entries[trace->nr_entries++] = addr;
>+}
>+
> static const struct stacktrace_ops save_stack_ops = {
> 	.warning = save_stack_warning,
> 	.warning_symbol = save_stack_warning_symbol,
>@@ -40,6 +53,13 @@ static const struct stacktrace_ops save_
> 	.address = save_stack_address,
> };
> 
>+static const struct stacktrace_ops save_stack_ops_nosched = {
>+	.warning = save_stack_warning,
>+	.warning_symbol = save_stack_warning_symbol,
>+	.stack = save_stack_stack,
>+	.address = save_stack_address_nosched,
>+};
>+
> /*
>  * Save stack-backtrace addresses into a stack_trace buffer.
>  */
>@@ -50,3 +70,10 @@ void save_stack_trace(struct stack_trace
> 		trace->entries[trace->nr_entries++] = ULONG_MAX;
> }
> EXPORT_SYMBOL(save_stack_trace);
>+
>+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
>+{
>+	dump_trace(tsk, NULL, NULL, &save_stack_ops_nosched, trace);
>+	if (trace->nr_entries < trace->max_entries)
>+		trace->entries[trace->nr_entries++] = ULONG_MAX;
>+}
>Index: linux-2.6.24-rc8/fs/proc/base.c
>===================================================================
>--- linux-2.6.24-rc8.orig/fs/proc/base.c
>+++ linux-2.6.24-rc8/fs/proc/base.c
>@@ -310,6 +310,79 @@ 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].backtrace[0]) {
>+			int q;
>+			seq_printf(m, "%i %li %li ",
>+				task->latency_record[i].count,
>+				task->latency_record[i].time,
>+				task->latency_record[i].max);
>+			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
>+				char sym[KSYM_NAME_LEN];
>+				char *c;
>+				if (!task->latency_record[i].backtrace[q])
>+					break;
>+				if (task->latency_record[i].backtrace[q]
>+								== ULONG_MAX)
>+					break;
>+				sprint_symbol(sym,
>+					task->latency_record[i].backtrace[q]);
>+				c = strchr(sym, '+');
>+				if (c)
>+					*c = 0;
>+				seq_printf(m, "%s ", sym);
>+			}
>+			seq_printf(m, "\n");
>+		}
>+
>+	}
>+	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)
>@@ -2230,6 +2303,9 @@ 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 +2631,9 @@ 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-rc8/include/linux/latencytop.h
>===================================================================
>--- /dev/null
>+++ linux-2.6.24-rc8/include/linux/latencytop.h
>@@ -0,0 +1,44 @@
>+/*
>+ * latencytop.h: Infrastructure for displaying latency
>+ *
>+ * (C) Copyright 2008 Intel Corporation
>+ * Author: Arjan van de Ven <arjan@linux.intel.com>
>+ *
>+ */
>+
>+#ifndef _INCLUDE_GUARD_LATENCYTOP_H_
>+#define _INCLUDE_GUARD_LATENCYTOP_H_
>+
>+#ifdef CONFIG_LATENCYTOP
>+
>+#define LT_SAVECOUNT		32
>+#define LT_BACKTRACEDEPTH	12
>+
>+struct latency_record {
>+	unsigned long	backtrace[LT_BACKTRACEDEPTH];
>+	unsigned int	count;
>+	unsigned long	time;
>+	unsigned long	max;
>+};
>+
>+
>+struct task_struct;
>+
>+void account_scheduler_latency(struct task_struct *task, int usecs, int inter);
>+
>+void clear_all_latency_tracing(struct task_struct *p);
>+
>+#else
>+
>+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-rc8/include/linux/sched.h
>===================================================================
>--- linux-2.6.24-rc8.orig/include/linux/sched.h
>+++ linux-2.6.24-rc8/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 +1179,10 @@ struct task_struct {
> 	int make_it_fail;
> #endif
> 	struct prop_local_single dirties;
>+#ifdef CONFIG_LATENCYTOP
>+	int latency_record_count;
>+	struct latency_record latency_record[LT_SAVECOUNT];
>+#endif
> };
> 
> /*
>Index: linux-2.6.24-rc8/include/linux/stacktrace.h
>===================================================================
>--- linux-2.6.24-rc8.orig/include/linux/stacktrace.h
>+++ linux-2.6.24-rc8/include/linux/stacktrace.h
>@@ -9,10 +9,13 @@ struct stack_trace {
> };
> 
> extern void save_stack_trace(struct stack_trace *trace);
>+extern void save_stack_trace_tsk(struct task_struct *tsk,
>+				struct stack_trace *trace);
> 
> extern void print_stack_trace(struct stack_trace *trace, int spaces);
> #else
> # define save_stack_trace(trace)			do { } while (0)
>+# define save_stack_trace_tsk(tsk, trace)		do { } while (0)
> # define print_stack_trace(trace, spaces)		do { } while (0)
> #endif
> 
>Index: linux-2.6.24-rc8/kernel/Makefile
>===================================================================
>--- linux-2.6.24-rc8.orig/kernel/Makefile
>+++ linux-2.6.24-rc8/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 <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
>Index: linux-2.6.24-rc8/kernel/fork.c
>===================================================================
>--- linux-2.6.24-rc8.orig/kernel/fork.c
>+++ linux-2.6.24-rc8/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-rc8/kernel/latencytop.c
>===================================================================
>--- /dev/null
>+++ linux-2.6.24-rc8/kernel/latencytop.c
>@@ -0,0 +1,241 @@
>+/*
>+ * latencytop.c: Latency display infrastructure
>+ *
>+ * (C) Copyright 2008 Intel Corporation
>+ * Author: Arjan van de Ven <arjan@linux.intel.com>
>+ *
>+ * 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/kallsyms.h>
>+#include <linux/seq_file.h>
>+#include <linux/notifier.h>
>+#include <linux/spinlock.h>
>+#include <linux/proc_fs.h>
>+#include <linux/module.h>
>+#include <linux/sched.h>
>+#include <linux/list.h>
>+#include <linux/slab.h>
>+#include <linux/stacktrace.h>
>+
>+static DEFINE_SPINLOCK(latency_lock);
>+
>+#define MAXLR 128
>+static struct latency_record latency_record[MAXLR];
>+
>+int latencytop_enabled;
>+
>+void clear_all_latency_tracing(struct task_struct *p)
>+{
>+	unsigned long flags;
>+
>+	if (!latencytop_enabled)
>+		return;
>+
>+	spin_lock_irqsave(&latency_lock, flags);
>+	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,
>+						struct latency_record *lat)
>+{
>+	int firstnonnull = MAXLR + 1;
>+	int i;
>+
>+	if (!latencytop_enabled)
>+		return;
>+
>+	/* skip kernel threads for now */
>+	if (!tsk->mm)
>+		return;
>+
>+	for (i = 0; i < MAXLR; i++) {
>+		int q;
>+		int same = 1;
>+		/* Nothing stored: */
>+		if (!latency_record[i].backtrace[0]) {
>+			if (firstnonnull > i)
>+				firstnonnull = i;
>+			continue;
>+		}
>+		for (q = 0 ; q < LT_BACKTRACEDEPTH ; q++) {
>+			if (latency_record[i].backtrace[q] !=
>+				lat->backtrace[q])
>+				same = 0;
>+			if (same && lat->backtrace[q] == 0)
>+				break;
>+			if (same && lat->backtrace[q] == ULONG_MAX)
>+				break;
>+		}
>+		if (same) {
>+			latency_record[i].count++;
>+			latency_record[i].time += lat->time;
>+			if (lat->time > latency_record[i].max)
>+				latency_record[i].max = lat->time;
>+			return;
>+		}
>+	}
>+
>+	i = firstnonnull;
>+	if (i >= MAXLR - 1)
>+		return;
>+
>+	/* Allocted a new one: */
>+	memcpy(&latency_record[i], lat, sizeof(struct latency_record));
>+}
>+
>+static inline void
>+store_stacktrace(struct task_struct *tsk, struct latency_record *lat)
>+{
>+	struct stack_trace trace;
>+
>+	memset(&trace, 0, sizeof(trace));
>+	trace.max_entries = LT_BACKTRACEDEPTH;
>+	trace.entries = &lat->backtrace[0];
>+	trace.skip = 0;
>+	save_stack_trace_tsk(tsk, &trace);
>+}
>+
>+void __sched
>+account_scheduler_latency(struct task_struct *tsk, int usecs, int inter)
>+{
>+	unsigned long flags;
>+	int i, q;
>+	struct latency_record lat;
>+
>+	if (!latencytop_enabled)
>+		return;
>+
>+	/* Long interruptible waits are generally user requested... */
>+	if (inter && usecs > 5000)
>+		return;
>+
>+	memset(&lat, 0, sizeof(lat));
>+	lat.count = 1;
>+	lat.time = usecs;
>+	lat.max = usecs;
>+	store_stacktrace(tsk, &lat);
>+
>+	spin_lock_irqsave(&latency_lock, flags);
>+
>+	account_global_scheduler_latency(tsk, &lat);
>+
>+	/*
>+	 * short term hack; if we're > 32 we stop; future we recycle:
>+	 */
>+	tsk->latency_record_count++;
>+	if (tsk->latency_record_count >= LT_SAVECOUNT)
>+		goto out_unlock;
>+
>+	for (i = 0; i < LT_SAVECOUNT ; i++) {
>+		struct latency_record *mylat;
>+		int same = 1;
>+		mylat = &tsk->latency_record[i];
>+		for (q = 0 ; q < LT_BACKTRACEDEPTH ; q++) {
>+			if (mylat->backtrace[q] !=
>+				lat.backtrace[q])
>+				same = 0;
>+			if (same && lat.backtrace[q] == 0)
>+				break;
>+			if (same && lat.backtrace[q] == ULONG_MAX)
>+				break;
>+		}
>+		if (same) {
>+			mylat->count++;
>+			mylat->time += lat.time;
>+			if (lat.time > mylat->max)
>+				mylat->max = lat.time;
>+			goto out_unlock;
>+		}
>+	}
>+
>+	/* Allocated a new one: */
>+	i = tsk->latency_record_count;
>+	memcpy(&tsk->latency_record[i], &lat, sizeof(struct latency_record));
>+
>+out_unlock:
>+	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].backtrace[0]) {
>+			int q;
>+			seq_printf(m, "%i %li %li ",
>+				latency_record[i].count,
>+				latency_record[i].time,
>+				latency_record[i].max);
>+			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
>+				char sym[KSYM_NAME_LEN];
>+				char *c;
>+				if (!latency_record[i].backtrace[q])
>+					break;
>+				if (latency_record[i].backtrace[q] == ULONG_MAX)
>+					break;
>+				sprint_symbol(sym,
>+						latency_record[i].backtrace[q]);
>+				c = strchr(sym, '+');
>+				if (c)
>+					*c = 0;
>+				seq_printf(m, "%s ", sym);
>+			}
>+			seq_printf(m, "\n");
>+		}
>+	}
>+	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-rc8/kernel/sched_fair.c
>===================================================================
>--- linux-2.6.24-rc8.orig/kernel/sched_fair.c
>+++ linux-2.6.24-rc8/kernel/sched_fair.c
>@@ -20,6 +20,8 @@
>  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
>  */
> 
>+#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-rc8/kernel/sysctl.c
>===================================================================
>--- linux-2.6.24-rc8.orig/kernel/sysctl.c
>+++ linux-2.6.24-rc8/kernel/sysctl.c
>@@ -81,6 +81,7 @@ extern int compat_log;
> extern int maps_protect;
> extern int sysctl_stat_interval;
> extern int audit_argv_kb;
>+extern int latencytop_enabled;
> 
> /* Constants used for minimum and  maximum */
> #ifdef CONFIG_DETECT_SOFTLOCKUP
>@@ -382,6 +383,15 @@ static struct ctl_table kern_table[] = {
> 		.proc_handler	= &proc_dointvec_taint,
> 	},
> #endif
>+#ifdef CONFIG_LATENCYTOP
>+	{
>+		.procname	= "latencytop",
>+		.data		= &latencytop_enabled,
>+		.maxlen		= sizeof(int),
>+		.mode		= 0644,
>+		.proc_handler	= &proc_dointvec,
>+	},
>+#endif
> #ifdef CONFIG_SECURITY_CAPABILITIES
> 	{
> 		.procname	= "cap-bound",
>Index: linux-2.6.24-rc8/lib/Kconfig.debug
>===================================================================
>--- linux-2.6.24-rc8.orig/lib/Kconfig.debug
>+++ linux-2.6.24-rc8/lib/Kconfig.debug
>@@ -517,4 +517,16 @@ config FAULT_INJECTION_STACKTRACE_FILTER
> 	help
> 	  Provide stacktrace filter for fault-injection capabilities
> 
>+config LATENCYTOP
>+	bool "Latency measuring infrastructure"
>+	select FRAME_POINTER if !MIPS
>+	select KALLSYMS
>+	select KALLSYMS_ALL
>+	select STACKTRACE
>+	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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Attachments on bug 431651: 294454