Messages in this thread Patch in this message | | | From | Alexey Dobriyan <> | Subject | [PATCH 12/13] proc: convert /proc/*/statm to _print_integer() | Date | Tue, 28 Aug 2018 02:15:02 +0300 |
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Benchmark pread("/proc/self/statm") 2^23 times:
6.135596793 seconds time elapsed ( +- 0.11% ) 5.685442773 seconds time elapsed ( +- 0.11% )
-7.3%
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> --- fs/proc/array.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c index 5016e03a4dba..d0565527166a 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -627,27 +627,27 @@ int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns, { unsigned long size = 0, resident = 0, shared = 0, text = 0, data = 0; struct mm_struct *mm = get_task_mm(task); + /* "%lu %lu %lu %lu 0 %lu 0\n" */ + char buf[5 * ((sizeof(long) * 5 / 2) + 1) + 2 + 2]; + char *p = buf + sizeof(buf); if (mm) { size = task_statm(mm, &shared, &text, &data, &resident); mmput(mm); } - /* - * For quick read, open code by putting numbers directly - * expected format is - * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n", - * size, resident, shared, text, data); - */ - seq_put_decimal_ull(m, "", size); - seq_put_decimal_ull(m, " ", resident); - seq_put_decimal_ull(m, " ", shared); - seq_put_decimal_ull(m, " ", text); - seq_put_decimal_ull(m, " ", 0); - seq_put_decimal_ull(m, " ", data); - seq_put_decimal_ull(m, " ", 0); - seq_putc(m, '\n'); - return 0; + p = memcpy(p - 3, " 0\n", 3); + p = _print_integer_ul(p, data); + p = memcpy(p - 3, " 0 ", 3); + p = _print_integer_ul(p, text); + *--p = ' '; + p = _print_integer_ul(p, shared); + *--p = ' '; + p = _print_integer_ul(p, resident); + *--p = ' '; + p = _print_integer_ul(p, size); + + return seq_write(m, p, buf + sizeof(buf) - p); } #ifdef CONFIG_PROC_CHILDREN -- 2.16.4
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