* [PATCH 1/4] seq_file: don't call bitmap_scnprintf_len()
@ 2008-10-12 9:29 Lai Jiangshan
2008-10-13 6:38 ` Alexey Dobriyan
0 siblings, 1 reply; 4+ messages in thread
From: Lai Jiangshan @ 2008-10-12 9:29 UTC (permalink / raw)
To: Andrew Morton
Cc: Alexey Dobriyan, Paul Menage, Paul Jackson,
Linux Kernel Mailing List
"m->count + len < m->size" is true commonly, so bitmap_scnprintf()
is commonly called. this fix saves a call to bitmap_scnprintf_len().
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/fs/seq_file.c b/fs/seq_file.c
index bd20f7f..11c85fe 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -452,17 +452,18 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
{
- size_t len = bitmap_scnprintf_len(nr_bits);
-
- if (m->count + len < m->size) {
- bitmap_scnprintf(m->buf + m->count, m->size - m->count,
- bits, nr_bits);
- m->count += len;
- return 0;
+ if (m->count < m->size) {
+ int len = bitmap_scnprintf(m->buf + m->count,
+ m->size - m->count, bits, nr_bits);
+ if (m->count + len < m->size) {
+ m->count += len;
+ return 0;
+ }
}
m->count = m->size;
return -1;
}
+EXPORT_SYMBOL(seq_bitmap);
static void *single_start(struct seq_file *p, loff_t *pos)
{
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH 1/4] seq_file: don't call bitmap_scnprintf_len()
2008-10-12 9:29 [PATCH 1/4] seq_file: don't call bitmap_scnprintf_len() Lai Jiangshan
@ 2008-10-13 6:38 ` Alexey Dobriyan
2008-10-13 7:17 ` Lai Jiangshan
0 siblings, 1 reply; 4+ messages in thread
From: Alexey Dobriyan @ 2008-10-13 6:38 UTC (permalink / raw)
To: Lai Jiangshan
Cc: Andrew Morton, Paul Menage, Paul Jackson,
Linux Kernel Mailing List
On Sun, Oct 12, 2008 at 05:29:17PM +0800, Lai Jiangshan wrote:
> "m->count + len < m->size" is true commonly, so bitmap_scnprintf()
> is commonly called. this fix saves a call to bitmap_scnprintf_len().
This saves a call if seq buffer is already full which is not a common
situation, so you're optimising for rare situations and adding branch
for common ones.
> --- a/fs/seq_file.c
> +++ b/fs/seq_file.c
> @@ -452,17 +452,18 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
>
> int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
> {
> - size_t len = bitmap_scnprintf_len(nr_bits);
> -
> - if (m->count + len < m->size) {
> - bitmap_scnprintf(m->buf + m->count, m->size - m->count,
> - bits, nr_bits);
> - m->count += len;
> - return 0;
> + if (m->count < m->size) {
> + int len = bitmap_scnprintf(m->buf + m->count,
> + m->size - m->count, bits, nr_bits);
> + if (m->count + len < m->size) {
> + m->count += len;
> + return 0;
> + }
> }
> m->count = m->size;
> return -1;
> }
> +EXPORT_SYMBOL(seq_bitmap);
Modular users, where are they?
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/4] seq_file: don't call bitmap_scnprintf_len()
2008-10-13 6:38 ` Alexey Dobriyan
@ 2008-10-13 7:17 ` Lai Jiangshan
2008-10-15 1:35 ` Lai Jiangshan
0 siblings, 1 reply; 4+ messages in thread
From: Lai Jiangshan @ 2008-10-13 7:17 UTC (permalink / raw)
To: Alexey Dobriyan
Cc: Andrew Morton, Paul Menage, Paul Jackson,
Linux Kernel Mailing List
Alexey Dobriyan wrote:
> On Sun, Oct 12, 2008 at 05:29:17PM +0800, Lai Jiangshan wrote:
>> "m->count + len < m->size" is true commonly, so bitmap_scnprintf()
>> is commonly called. this fix saves a call to bitmap_scnprintf_len().
>
> This saves a call if seq buffer is already full which is not a common
> situation, so you're optimising for rare situations and adding branch
> for common ones.
Hi Alexey
I think this saves a call if seq buffer is _not_ full after called.
since calling bitmap_scnprintf() is the common situation. so we use
the return value of bitmap_scnprintf() instead of bitmap_scnprintf_len().
In old code bitmap_scnprintf_len() and bitmap_scnprintf() must be called
commonly.
Thanks Lai.
>
>> --- a/fs/seq_file.c
>> +++ b/fs/seq_file.c
>> @@ -452,17 +452,18 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
>>
>> int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
>> {
>> - size_t len = bitmap_scnprintf_len(nr_bits);
>> -
>> - if (m->count + len < m->size) {
>> - bitmap_scnprintf(m->buf + m->count, m->size - m->count,
>> - bits, nr_bits);
>> - m->count += len;
>> - return 0;
>> + if (m->count < m->size) {
>> + int len = bitmap_scnprintf(m->buf + m->count,
>> + m->size - m->count, bits, nr_bits);
>> + if (m->count + len < m->size) {
>> + m->count += len;
>> + return 0;
>> + }
>> }
>> m->count = m->size;
>> return -1;
>> }
>> +EXPORT_SYMBOL(seq_bitmap);
>
> Modular users, where are they?
>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/4] seq_file: don't call bitmap_scnprintf_len()
2008-10-13 7:17 ` Lai Jiangshan
@ 2008-10-15 1:35 ` Lai Jiangshan
0 siblings, 0 replies; 4+ messages in thread
From: Lai Jiangshan @ 2008-10-15 1:35 UTC (permalink / raw)
To: Alexey Dobriyan
Cc: Andrew Morton, Paul Menage, Paul Jackson,
Linux Kernel Mailing List
Lai Jiangshan wrote:
> Alexey Dobriyan wrote:
>> On Sun, Oct 12, 2008 at 05:29:17PM +0800, Lai Jiangshan wrote:
>>> "m->count + len < m->size" is true commonly, so bitmap_scnprintf()
>>> is commonly called. this fix saves a call to bitmap_scnprintf_len().
>> This saves a call if seq buffer is already full which is not a common
>> situation, so you're optimising for rare situations and adding branch
>> for common ones.
>
> Hi Alexey
>
> I think this saves a call if seq buffer is _not_ full after called.
>
> since calling bitmap_scnprintf() is the common situation. so we use
> the return value of bitmap_scnprintf() instead of bitmap_scnprintf_len().
>
> In old code bitmap_scnprintf_len() and bitmap_scnprintf() must be called
> commonly.
>
> Thanks Lai.
Hi, Alexey,
Have noticed this comment? I hold my ground, ;-)
And seq_cpumask_list(), seq_nodemask_list() are needed for print mask
safely, Should I send independent patches for them if we can't
make an agreement about this fix.
Lai
>
>>> --- a/fs/seq_file.c
>>> +++ b/fs/seq_file.c
>>> @@ -452,17 +452,18 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
>>>
>>> int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
>>> {
>>> - size_t len = bitmap_scnprintf_len(nr_bits);
>>> -
>>> - if (m->count + len < m->size) {
>>> - bitmap_scnprintf(m->buf + m->count, m->size - m->count,
>>> - bits, nr_bits);
>>> - m->count += len;
>>> - return 0;
>>> + if (m->count < m->size) {
>>> + int len = bitmap_scnprintf(m->buf + m->count,
>>> + m->size - m->count, bits, nr_bits);
>>> + if (m->count + len < m->size) {
>>> + m->count += len;
>>> + return 0;
>>> + }
>>> }
>>> m->count = m->size;
>>> return -1;
>>> }
>>> +EXPORT_SYMBOL(seq_bitmap);
>> Modular users, where are they?
>>
>>
>>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2008-10-15 1:37 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2008-10-12 9:29 [PATCH 1/4] seq_file: don't call bitmap_scnprintf_len() Lai Jiangshan
2008-10-13 6:38 ` Alexey Dobriyan
2008-10-13 7:17 ` Lai Jiangshan
2008-10-15 1:35 ` Lai Jiangshan
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