diff options
Diffstat (limited to 'kernel/latencytop.c')
| -rw-r--r-- | kernel/latencytop.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/kernel/latencytop.c b/kernel/latencytop.c new file mode 100644 index 00000000000..b4e3c85abe7 --- /dev/null +++ b/kernel/latencytop.c @@ -0,0 +1,239 @@ +/* + * 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); |