From 0e3dc019143104a6e676287b1e453cccd7add404 Mon Sep 17 00:00:00 2001 From: Andrei Vagin Date: Tue, 10 Apr 2018 16:30:44 -0700 Subject: [PATCH] procfs: add seq_put_hex_ll to speed up /proc/pid/maps seq_put_hex_ll() prints a number in hexadecimal notation and works faster than seq_printf(). == test.py num = 0 with open("/proc/1/maps") as f: while num < 10000 : data = f.read() f.seek(0, 0) num = num + 1 == == Before patch == $ time python test.py real 0m1.561s user 0m0.257s sys 0m1.302s == After patch == $ time python test.py real 0m0.986s user 0m0.279s sys 0m0.707s $ perf -g record python test.py: == Before patch == - 67.42% 2.82% python [kernel.kallsyms] [k] show_map_vma.isra.22 - 64.60% show_map_vma.isra.22 - 44.98% seq_printf - seq_vprintf - vsnprintf + 14.85% number + 12.22% format_decode 5.56% memcpy_erms + 15.06% seq_path + 4.42% seq_pad + 2.45% __GI___libc_read == After patch == - 47.35% 3.38% python [kernel.kallsyms] [k] show_map_vma.isra.23 - 43.97% show_map_vma.isra.23 + 20.84% seq_path - 15.73% show_vma_header_prefix 10.55% seq_put_hex_ll + 2.65% seq_put_decimal_ull 0.95% seq_putc + 6.96% seq_pad + 2.94% __GI___libc_read [avagin@openvz.org: use unsigned int instead of int where it is suitable] Link: http://lkml.kernel.org/r/20180214025619.4005-1-avagin@openvz.org [avagin@openvz.org: v2] Link: http://lkml.kernel.org/r/20180117082050.25406-1-avagin@openvz.org Link: http://lkml.kernel.org/r/20180112185812.7710-1-avagin@openvz.org Signed-off-by: Andrei Vagin Cc: Alexey Dobriyan Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 21 ++++++++++-------- fs/seq_file.c | 46 ++++++++++++++++++++++++++++++++++++++++ include/linux/seq_file.h | 3 +++ 3 files changed, 61 insertions(+), 9 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index ec6d2983a5cb..b66fc8de7d34 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -287,15 +287,18 @@ static void show_vma_header_prefix(struct seq_file *m, dev_t dev, unsigned long ino) { seq_setwidth(m, 25 + sizeof(void *) * 6 - 1); - seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ", - start, - end, - flags & VM_READ ? 'r' : '-', - flags & VM_WRITE ? 'w' : '-', - flags & VM_EXEC ? 'x' : '-', - flags & VM_MAYSHARE ? 's' : 'p', - pgoff, - MAJOR(dev), MINOR(dev), ino); + seq_put_hex_ll(m, NULL, start, 8); + seq_put_hex_ll(m, "-", end, 8); + seq_putc(m, ' '); + seq_putc(m, flags & VM_READ ? 'r' : '-'); + seq_putc(m, flags & VM_WRITE ? 'w' : '-'); + seq_putc(m, flags & VM_EXEC ? 'x' : '-'); + seq_putc(m, flags & VM_MAYSHARE ? 's' : 'p'); + seq_put_hex_ll(m, " ", pgoff, 8); + seq_put_hex_ll(m, " ", MAJOR(dev), 2); + seq_put_hex_ll(m, ":", MINOR(dev), 2); + seq_put_decimal_ull(m, " ", ino); + seq_putc(m, ' '); } static void diff --git a/fs/seq_file.c b/fs/seq_file.c index eea09f6d8830..cde1bdbf7801 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -715,6 +715,52 @@ void seq_put_decimal_ull(struct seq_file *m, const char *delimiter, } EXPORT_SYMBOL(seq_put_decimal_ull); +/** + * seq_put_hex_ll - put a number in hexadecimal notation + * @m: seq_file identifying the buffer to which data should be written + * @delimiter: a string which is printed before the number + * @v: the number + * @width: a minimum field width + * + * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v) + * + * This routine is very quick when you show lots of numbers. + * In usual cases, it will be better to use seq_printf(). It's easier to read. + */ +void seq_put_hex_ll(struct seq_file *m, const char *delimiter, + unsigned long long v, unsigned int width) +{ + unsigned int len; + int i; + + if (delimiter && delimiter[0]) { + if (delimiter[1] == 0) + seq_putc(m, delimiter[0]); + else + seq_puts(m, delimiter); + } + + /* If x is 0, the result of __builtin_clzll is undefined */ + if (v == 0) + len = 1; + else + len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4; + + if (len < width) + len = width; + + if (m->count + len > m->size) { + seq_set_overflow(m); + return; + } + + for (i = len - 1; i >= 0; i--) { + m->buf[m->count + i] = hex_asc[0xf & v]; + v = v >> 4; + } + m->count += len; +} + void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num) { int len; diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index ab437dd2e3b9..599e145f4917 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -121,6 +121,9 @@ void seq_puts(struct seq_file *m, const char *s); void seq_put_decimal_ull(struct seq_file *m, const char *delimiter, unsigned long long num); void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num); +void seq_put_hex_ll(struct seq_file *m, const char *delimiter, + unsigned long long v, unsigned int width); + void seq_escape(struct seq_file *m, const char *s, const char *esc); void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,