![KAMEZAWA Hiroyuki](/assets/img/avatar_default.png)
== stat_check.py num = 0 with open("/proc/stat") as f: while num < 1000 : data = f.read() f.seek(0, 0) num = num + 1 == perf shows 20.39% stat_check.py [kernel.kallsyms] [k] format_decode 13.41% stat_check.py [kernel.kallsyms] [k] number 12.61% stat_check.py [kernel.kallsyms] [k] vsnprintf 10.85% stat_check.py [kernel.kallsyms] [k] memcpy 4.85% stat_check.py [kernel.kallsyms] [k] radix_tree_lookup 4.43% stat_check.py [kernel.kallsyms] [k] seq_printf This patch removes most of calls to vsnprintf() by adding num_to_str() and seq_print_decimal_ull(), which prints decimal numbers without rich functions provided by printf(). On my 8cpu box. == Before patch == [root@bluextal test]# time ./stat_check.py real 0m0.150s user 0m0.026s sys 0m0.121s == After patch == [root@bluextal test]# time ./stat_check.py real 0m0.055s user 0m0.022s sys 0m0.030s [akpm@linux-foundation.org: remove incorrect comment, use less statck in num_to_str(), move comment from .h to .c, simplify seq_put_decimal_ull()] [andrea@betterlinux.com: avoid breaking the ABI in /proc/stat] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrea Righi <andrea@betterlinux.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Turner <pjt@google.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
158 lines
4.5 KiB
C
158 lines
4.5 KiB
C
#ifndef _LINUX_SEQ_FILE_H
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#define _LINUX_SEQ_FILE_H
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/mutex.h>
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#include <linux/cpumask.h>
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#include <linux/nodemask.h>
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struct seq_operations;
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struct file;
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struct path;
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struct inode;
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struct dentry;
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struct seq_file {
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char *buf;
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size_t size;
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size_t from;
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size_t count;
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loff_t index;
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loff_t read_pos;
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u64 version;
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struct mutex lock;
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const struct seq_operations *op;
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int poll_event;
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void *private;
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};
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struct seq_operations {
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void * (*start) (struct seq_file *m, loff_t *pos);
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void (*stop) (struct seq_file *m, void *v);
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void * (*next) (struct seq_file *m, void *v, loff_t *pos);
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int (*show) (struct seq_file *m, void *v);
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};
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#define SEQ_SKIP 1
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/**
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* seq_get_buf - get buffer to write arbitrary data to
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* @m: the seq_file handle
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* @bufp: the beginning of the buffer is stored here
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*
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* Return the number of bytes available in the buffer, or zero if
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* there's no space.
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*/
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static inline size_t seq_get_buf(struct seq_file *m, char **bufp)
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{
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BUG_ON(m->count > m->size);
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if (m->count < m->size)
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*bufp = m->buf + m->count;
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else
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*bufp = NULL;
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return m->size - m->count;
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}
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/**
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* seq_commit - commit data to the buffer
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* @m: the seq_file handle
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* @num: the number of bytes to commit
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*
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* Commit @num bytes of data written to a buffer previously acquired
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* by seq_buf_get. To signal an error condition, or that the data
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* didn't fit in the available space, pass a negative @num value.
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*/
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static inline void seq_commit(struct seq_file *m, int num)
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{
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if (num < 0) {
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m->count = m->size;
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} else {
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BUG_ON(m->count + num > m->size);
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m->count += num;
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}
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}
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char *mangle_path(char *s, const char *p, const char *esc);
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int seq_open(struct file *, const struct seq_operations *);
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ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);
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loff_t seq_lseek(struct file *, loff_t, int);
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int seq_release(struct inode *, struct file *);
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int seq_escape(struct seq_file *, const char *, const char *);
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int seq_putc(struct seq_file *m, char c);
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int seq_puts(struct seq_file *m, const char *s);
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int seq_write(struct seq_file *seq, const void *data, size_t len);
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__printf(2, 3) int seq_printf(struct seq_file *, const char *, ...);
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int seq_path(struct seq_file *, const struct path *, const char *);
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int seq_dentry(struct seq_file *, struct dentry *, const char *);
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int seq_path_root(struct seq_file *m, const struct path *path,
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const struct path *root, const char *esc);
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int seq_bitmap(struct seq_file *m, const unsigned long *bits,
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unsigned int nr_bits);
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static inline int seq_cpumask(struct seq_file *m, const struct cpumask *mask)
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{
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return seq_bitmap(m, cpumask_bits(mask), nr_cpu_ids);
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}
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static inline int seq_nodemask(struct seq_file *m, nodemask_t *mask)
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{
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return seq_bitmap(m, mask->bits, MAX_NUMNODES);
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}
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int seq_bitmap_list(struct seq_file *m, const unsigned long *bits,
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unsigned int nr_bits);
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static inline int seq_cpumask_list(struct seq_file *m,
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const struct cpumask *mask)
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{
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return seq_bitmap_list(m, cpumask_bits(mask), nr_cpu_ids);
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}
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static inline int seq_nodemask_list(struct seq_file *m, nodemask_t *mask)
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{
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return seq_bitmap_list(m, mask->bits, MAX_NUMNODES);
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}
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int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
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int single_release(struct inode *, struct file *);
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void *__seq_open_private(struct file *, const struct seq_operations *, int);
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int seq_open_private(struct file *, const struct seq_operations *, int);
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int seq_release_private(struct inode *, struct file *);
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int seq_put_decimal_ull(struct seq_file *m, char delimiter,
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unsigned long long num);
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#define SEQ_START_TOKEN ((void *)1)
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/*
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* Helpers for iteration over list_head-s in seq_files
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*/
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extern struct list_head *seq_list_start(struct list_head *head,
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loff_t pos);
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extern struct list_head *seq_list_start_head(struct list_head *head,
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loff_t pos);
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extern struct list_head *seq_list_next(void *v, struct list_head *head,
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loff_t *ppos);
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/*
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* Helpers for iteration over hlist_head-s in seq_files
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*/
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extern struct hlist_node *seq_hlist_start(struct hlist_head *head,
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loff_t pos);
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extern struct hlist_node *seq_hlist_start_head(struct hlist_head *head,
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loff_t pos);
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extern struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
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loff_t *ppos);
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extern struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
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loff_t pos);
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extern struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
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loff_t pos);
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extern struct hlist_node *seq_hlist_next_rcu(void *v,
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struct hlist_head *head,
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loff_t *ppos);
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#endif
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