* [PATCH 1/2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps
@ 2018-01-12 18:58 Andrei Vagin
2018-01-12 18:58 ` [PATCH 2/2] procfs: optimize seq_pad() " Andrei Vagin
2018-01-12 23:33 ` [PATCH 1/2] procfs: add seq_put_hex_ll " Andrew Morton
0 siblings, 2 replies; 8+ messages in thread
From: Andrei Vagin @ 2018-01-12 18:58 UTC (permalink / raw)
To: linux-fsdevel
Cc: Andrew Morton, Andrei Vagin, Alexey Dobriyan, KAMEZAWA Hiroyuki
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
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
---
fs/proc/task_mmu.c | 21 ++++++++------
fs/seq_file.c | 74 ++++++++++++++++++++++++++++++++++++++++--------
include/linux/seq_file.h | 3 ++
3 files changed, 77 insertions(+), 21 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 339e4c1c044d..3a08685ef27c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -282,15 +282,18 @@ 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 4be761c1a03d..fb37ec42fae2 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -670,6 +670,26 @@ void seq_puts(struct seq_file *m, const char *s)
}
EXPORT_SYMBOL(seq_puts);
+static inline void seq_put_delimeter(struct seq_file *m, const char *delimiter)
+{
+ int len;
+
+ if (!delimiter || !delimiter[0])
+ return;
+
+ if (delimiter[1] == 0)
+ return seq_putc(m, delimiter[0]);
+
+ len = strlen(delimiter);
+ if (m->count + len >= m->size) {
+ seq_set_overflow(m);
+ return;
+ }
+
+ memcpy(m->buf + m->count, delimiter, len);
+ m->count += len;
+}
+
/*
* A helper routine for putting decimal numbers without rich format of printf().
* only 'unsigned long long' is supported.
@@ -685,12 +705,7 @@ void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
goto overflow;
- len = strlen(delimiter);
- if (m->count + len >= m->size)
- goto overflow;
-
- memcpy(m->buf + m->count, delimiter, len);
- m->count += len;
+ seq_put_delimeter(m, delimiter);
if (m->count + 1 >= m->size)
goto overflow;
@@ -712,6 +727,46 @@ 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, "0x08llx", 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, int width)
+{
+ int i, len;
+
+ seq_put_delimeter(m, delimiter);
+
+ len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
+
+ if (unlikely(len == 0))
+ len = 1;
+
+ if (len < width)
+ len = width;
+
+ if (m->count + len > m->size)
+ goto overflow;
+
+ for (i = len - 1; i >= 0; i--) {
+ m->buf[m->count + i] = hex_asc[0xf & v];
+ v = v >> 4;
+ }
+ m->count += len;
+ return;
+overflow:
+ seq_set_overflow(m);
+}
+
void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
{
int len;
@@ -719,12 +774,7 @@ void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num
if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
goto overflow;
- len = strlen(delimiter);
- if (m->count + len >= m->size)
- goto overflow;
-
- memcpy(m->buf + m->count, delimiter, len);
- m->count += len;
+ seq_put_delimeter(m, delimiter);
if (m->count + 2 >= m->size)
goto overflow;
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 09c6e28746f9..53f238934d7f 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, 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,
--
2.13.6
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 2/2] procfs: optimize seq_pad() to speed up /proc/pid/maps
2018-01-12 18:58 [PATCH 1/2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps Andrei Vagin
@ 2018-01-12 18:58 ` Andrei Vagin
2018-01-12 23:33 ` [PATCH 1/2] procfs: add seq_put_hex_ll " Andrew Morton
1 sibling, 0 replies; 8+ messages in thread
From: Andrei Vagin @ 2018-01-12 18:58 UTC (permalink / raw)
To: linux-fsdevel
Cc: Andrew Morton, Andrei Vagin, Alexey Dobriyan, KAMEZAWA Hiroyuki
seq_printf() is slow and it can be replaced by memset() in this case.
== 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 0m0.986s
user 0m0.279s
sys 0m0.707s
== After patch ==
$ time python test.py
real 0m0.932s
user 0m0.261s
sys 0m0.669s
$ perf record -g python test.py
== Before 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
+ 6.96% seq_pad
+ 2.94% __GI___libc_read
== After patch ==
- 44.01% 0.34% python [kernel.kallsyms] [k] show_pid_map
- 43.67% show_pid_map
- 42.91% show_map_vma.isra.23
+ 21.55% seq_path
- 15.68% show_vma_header_prefix
+ 2.08% seq_pad
0.55% seq_putc
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
---
fs/seq_file.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/seq_file.c b/fs/seq_file.c
index fb37ec42fae2..0ee52a372b66 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -829,8 +829,14 @@ EXPORT_SYMBOL(seq_write);
void seq_pad(struct seq_file *m, char c)
{
int size = m->pad_until - m->count;
- if (size > 0)
- seq_printf(m, "%*s", size, "");
+ if (size > 0) {
+ if (size + m->count > m->size) {
+ seq_set_overflow(m);
+ return;
+ }
+ memset(m->buf + m->count, ' ', size);
+ m->count += size;
+ }
if (c)
seq_putc(m, c);
}
--
2.13.6
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps
2018-01-12 18:58 [PATCH 1/2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps Andrei Vagin
2018-01-12 18:58 ` [PATCH 2/2] procfs: optimize seq_pad() " Andrei Vagin
@ 2018-01-12 23:33 ` Andrew Morton
2018-01-15 7:04 ` Andrei Vagin
2018-01-17 8:20 ` [PATCH v2] " Andrei Vagin
1 sibling, 2 replies; 8+ messages in thread
From: Andrew Morton @ 2018-01-12 23:33 UTC (permalink / raw)
To: Andrei Vagin; +Cc: linux-fsdevel, Alexey Dobriyan, KAMEZAWA Hiroyuki
On Fri, 12 Jan 2018 10:58:11 -0800 Andrei Vagin <avagin@openvz.org> wrote:
> seq_put_hex_ll() prints a number in hexadecimal notation and works
> faster than seq_printf().
>
> ...
>
> --- a/fs/seq_file.c
> +++ b/fs/seq_file.c
> @@ -670,6 +670,26 @@ void seq_puts(struct seq_file *m, const char *s)
> }
> EXPORT_SYMBOL(seq_puts);
>
> +static inline void seq_put_delimeter(struct seq_file *m, const char *delimiter)
> +{
> + int len;
> +
> + if (!delimiter || !delimiter[0])
> + return;
> +
> + if (delimiter[1] == 0)
> + return seq_putc(m, delimiter[0]);
> +
> + len = strlen(delimiter);
> + if (m->count + len >= m->size) {
> + seq_set_overflow(m);
> + return;
> + }
> +
> + memcpy(m->buf + m->count, delimiter, len);
> + m->count += len;
> +}
Can we please have a nice comment describing this function's role and
behaviour?
I don't think the `inline' is needed or desirable - gcc can figure that
out, and with three callsites a `noinline' would be more justified!
That `return seq_putc(...)' will generate a warning in some situations
- seq_putc() returns void. Let's split it into 'seq_putc(...);
return;' please.
> +/**
> + * 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, "0x08llx", 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, int width)
> +{
> + int i, len;
> +
> + seq_put_delimeter(m, delimiter);
> +
> + len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
> +
> + if (unlikely(len == 0))
> + len = 1;
> +
> + if (len < width)
> + len = width;
> +
> + if (m->count + len > m->size)
> + goto overflow;
> +
> + for (i = len - 1; i >= 0; i--) {
> + m->buf[m->count + i] = hex_asc[0xf & v];
> + v = v >> 4;
> + }
> + m->count += len;
> + return;
> +overflow:
> + seq_set_overflow(m);
> +}
I don't think we need the goto. Just do "seq_set_overflow(m); return;".
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps
2018-01-12 23:33 ` [PATCH 1/2] procfs: add seq_put_hex_ll " Andrew Morton
@ 2018-01-15 7:04 ` Andrei Vagin
2018-01-17 8:20 ` [PATCH v2] " Andrei Vagin
1 sibling, 0 replies; 8+ messages in thread
From: Andrei Vagin @ 2018-01-15 7:04 UTC (permalink / raw)
To: Andrew Morton
Cc: Andrei Vagin, linux-fsdevel, Alexey Dobriyan, KAMEZAWA Hiroyuki
On Fri, Jan 12, 2018 at 03:33:04PM -0800, Andrew Morton wrote:
> On Fri, 12 Jan 2018 10:58:11 -0800 Andrei Vagin <avagin@openvz.org> wrote:
>
> > seq_put_hex_ll() prints a number in hexadecimal notation and works
> > faster than seq_printf().
> >
> > ...
> >
> > --- a/fs/seq_file.c
> > +++ b/fs/seq_file.c
> > @@ -670,6 +670,26 @@ void seq_puts(struct seq_file *m, const char *s)
> > }
> > EXPORT_SYMBOL(seq_puts);
> >
> > +static inline void seq_put_delimeter(struct seq_file *m, const char *delimiter)
> > +{
> > + int len;
> > +
> > + if (!delimiter || !delimiter[0])
> > + return;
> > +
> > + if (delimiter[1] == 0)
> > + return seq_putc(m, delimiter[0]);
> > +
> > + len = strlen(delimiter);
> > + if (m->count + len >= m->size) {
> > + seq_set_overflow(m);
> > + return;
> > + }
> > +
> > + memcpy(m->buf + m->count, delimiter, len);
> > + m->count += len;
> > +}
>
> Can we please have a nice comment describing this function's role and
> behaviour?
seq_put_decimal_* and seq_put_hex_ll prints a string before printing a
number. Originaly it was just one symbol, it is probably a reason why it
is called delimeter.
I added an optimization for a case when delimiter is one symbol, and
found that it sinificantly affect perfomance (about 13% for
/proc/pid/maps):
Without this optimization:
[root@fc24 ~]# time python test.py
real 0m9.105s
user 0m2.200s
sys 0m6.901s
With this optimization:
[root@fc24 ~]# time python test.py
real 0m8.097s
user 0m1.994s
sys 0m6.102s
If inline is replaced by noinline
[root@fc24 ~]# time python test.py
real 0m8.263s
user 0m2.058s
sys 0m6.200s
[root@fc24 ~]# cat test.py
#!/usr/bin/env python2
num = 0
with open("/proc/1/maps") as f:
for x in xrange(100000):
data = f.read()
f.seek(0, 0)
Andrew, thank you for the review, I will send a fixed patch soon.
>
> I don't think the `inline' is needed or desirable - gcc can figure that
> out, and with three callsites a `noinline' would be more justified!
>
> That `return seq_putc(...)' will generate a warning in some situations
> - seq_putc() returns void. Let's split it into 'seq_putc(...);
> return;' please.
>
> > +/**
> > + * 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, "0x08llx", 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, int width)
> > +{
> > + int i, len;
> > +
> > + seq_put_delimeter(m, delimiter);
> > +
> > + len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
> > +
> > + if (unlikely(len == 0))
> > + len = 1;
> > +
> > + if (len < width)
> > + len = width;
> > +
> > + if (m->count + len > m->size)
> > + goto overflow;
> > +
> > + for (i = len - 1; i >= 0; i--) {
> > + m->buf[m->count + i] = hex_asc[0xf & v];
> > + v = v >> 4;
> > + }
> > + m->count += len;
> > + return;
> > +overflow:
> > + seq_set_overflow(m);
> > +}
>
> I don't think we need the goto. Just do "seq_set_overflow(m); return;".
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps
2018-01-12 23:33 ` [PATCH 1/2] procfs: add seq_put_hex_ll " Andrew Morton
2018-01-15 7:04 ` Andrei Vagin
@ 2018-01-17 8:20 ` Andrei Vagin
2018-02-09 13:48 ` Alexey Dobriyan
1 sibling, 1 reply; 8+ messages in thread
From: Andrei Vagin @ 2018-01-17 8:20 UTC (permalink / raw)
To: linux-fsdevel, Andrew Morton
Cc: Andrei Vagin, Alexey Dobriyan, KAMEZAWA Hiroyuki
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
v2: don't create a separate function to print delimiter and a few fixes
to make code more readable.
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
---
fs/proc/task_mmu.c | 21 ++++++++++++---------
fs/seq_file.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/seq_file.h | 3 +++
3 files changed, 60 insertions(+), 9 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 339e4c1c044d..3a08685ef27c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -282,15 +282,18 @@ 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 bce089cc1771..d2885220ecf7 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -712,6 +712,51 @@ 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, "0x08llx", 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, int width)
+{
+ int i, len;
+
+ 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 09c6e28746f9..53f238934d7f 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, 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,
--
2.13.6
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps
2018-01-17 8:20 ` [PATCH v2] " Andrei Vagin
@ 2018-02-09 13:48 ` Alexey Dobriyan
2018-02-10 7:50 ` Andrei Vagin
0 siblings, 1 reply; 8+ messages in thread
From: Alexey Dobriyan @ 2018-02-09 13:48 UTC (permalink / raw)
To: Andrei Vagin; +Cc: linux-fsdevel, Andrew Morton, KAMEZAWA Hiroyuki
On Wed, Jan 17, 2018 at 12:20:50AM -0800, Andrei Vagin wrote:
> + * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "0x08llx", v)
No, it is not. Scratch "0x".
> +void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
> + unsigned long long v, int width)
I understand that "unsigned long long" mimics decimal counterpart,
but in thie case everything is "unsigned long" including ->vm_pgoff.
Also, width should be unsigned for the common case of %08lx
(and "len" too)
> +{
> + int i, len;
> +
> + 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;
> +}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps
2018-02-09 13:48 ` Alexey Dobriyan
@ 2018-02-10 7:50 ` Andrei Vagin
2018-02-12 22:15 ` Alexey Dobriyan
0 siblings, 1 reply; 8+ messages in thread
From: Andrei Vagin @ 2018-02-10 7:50 UTC (permalink / raw)
To: Alexey Dobriyan
Cc: Andrei Vagin, linux-fsdevel, Andrew Morton, KAMEZAWA Hiroyuki
On Fri, Feb 09, 2018 at 04:48:47PM +0300, Alexey Dobriyan wrote:
> On Wed, Jan 17, 2018 at 12:20:50AM -0800, Andrei Vagin wrote:
> > + * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "0x08llx", v)
>
> No, it is not. Scratch "0x".
will fix
>
> > +void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
> > + unsigned long long v, int width)
>
> I understand that "unsigned long long" mimics decimal counterpart,
> but in thie case everything is "unsigned long" including ->vm_pgoff.
I've checked that the performance is the same for "unsigned long long" and
"unsigned long". Do we have other reasons to use "unsigned long" rather
than "unsigned long long"?
>
> Also, width should be unsigned for the common case of %08lx
> (and "len" too)
will fix
Thank you for the review.
>
> > +{
> > + int i, len;
> > +
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps
2018-02-10 7:50 ` Andrei Vagin
@ 2018-02-12 22:15 ` Alexey Dobriyan
0 siblings, 0 replies; 8+ messages in thread
From: Alexey Dobriyan @ 2018-02-12 22:15 UTC (permalink / raw)
To: Andrei Vagin
Cc: Andrei Vagin, linux-fsdevel, Andrew Morton, KAMEZAWA Hiroyuki
On Fri, Feb 09, 2018 at 11:50:01PM -0800, Andrei Vagin wrote:
> On Fri, Feb 09, 2018 at 04:48:47PM +0300, Alexey Dobriyan wrote:
> > On Wed, Jan 17, 2018 at 12:20:50AM -0800, Andrei Vagin wrote:
> > > + * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "0x08llx", v)
> >
> > No, it is not. Scratch "0x".
>
> will fix
> >
> > > +void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
> > > + unsigned long long v, int width)
> >
> > I understand that "unsigned long long" mimics decimal counterpart,
> > but in thie case everything is "unsigned long" including ->vm_pgoff.
>
> I've checked that the performance is the same for "unsigned long long" and
> "unsigned long". Do we have other reasons to use "unsigned long" rather
> than "unsigned long long"?
On 32-bit those types are different.
But I guess as seq_put_decimal is ull, it is worse to deviate.
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2018-02-12 22:15 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-01-12 18:58 [PATCH 1/2] procfs: add seq_put_hex_ll to speed up /proc/pid/maps Andrei Vagin
2018-01-12 18:58 ` [PATCH 2/2] procfs: optimize seq_pad() " Andrei Vagin
2018-01-12 23:33 ` [PATCH 1/2] procfs: add seq_put_hex_ll " Andrew Morton
2018-01-15 7:04 ` Andrei Vagin
2018-01-17 8:20 ` [PATCH v2] " Andrei Vagin
2018-02-09 13:48 ` Alexey Dobriyan
2018-02-10 7:50 ` Andrei Vagin
2018-02-12 22:15 ` Alexey Dobriyan
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