* [RESEND PATCH] fs/buffer.c: exit if already confirmed page has dirty and writeback buffers
@ 2013-11-05 10:02 Gu Zheng
2013-11-07 11:44 ` Jan Kara
0 siblings, 1 reply; 3+ messages in thread
From: Gu Zheng @ 2013-11-05 10:02 UTC (permalink / raw)
To: Al Viro; +Cc: fsdevel, linux-kernel
Stop the loop of iterating bh if we have confirmed page
has dirty and writeback buffers.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
---
fs/buffer.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 6024877..519cc5c 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -112,7 +112,7 @@ void buffer_check_dirty_writeback(struct page *page,
*dirty = true;
bh = bh->b_this_page;
- } while (bh != head);
+ } while ((bh != head) && !(*writeback && *dirty));
}
EXPORT_SYMBOL(buffer_check_dirty_writeback);
--
1.7.7
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RESEND PATCH] fs/buffer.c: exit if already confirmed page has dirty and writeback buffers
2013-11-05 10:02 [RESEND PATCH] fs/buffer.c: exit if already confirmed page has dirty and writeback buffers Gu Zheng
@ 2013-11-07 11:44 ` Jan Kara
2013-11-08 9:56 ` Gu Zheng
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kara @ 2013-11-07 11:44 UTC (permalink / raw)
To: Gu Zheng; +Cc: Al Viro, fsdevel, linux-kernel
On Tue 05-11-13 18:02:03, Gu Zheng wrote:
> Stop the loop of iterating bh if we have confirmed page
> has dirty and writeback buffers.
Thanks for the patch. What I'm somewhat missing here is a motivation of
the patch. For the common case where blocksize == pagesize this is a noop
(only adds some code). For the case where blocksize < pagesize we can
possibly save checking some buffers but how common is that going be? Does
that minimal speed up outweight the cost of additional check / code
complication?
Honza
>
> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
> ---
> fs/buffer.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 6024877..519cc5c 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -112,7 +112,7 @@ void buffer_check_dirty_writeback(struct page *page,
> *dirty = true;
>
> bh = bh->b_this_page;
> - } while (bh != head);
> + } while ((bh != head) && !(*writeback && *dirty));
> }
> EXPORT_SYMBOL(buffer_check_dirty_writeback);
>
> --
> 1.7.7
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RESEND PATCH] fs/buffer.c: exit if already confirmed page has dirty and writeback buffers
2013-11-07 11:44 ` Jan Kara
@ 2013-11-08 9:56 ` Gu Zheng
0 siblings, 0 replies; 3+ messages in thread
From: Gu Zheng @ 2013-11-08 9:56 UTC (permalink / raw)
To: Jan Kara; +Cc: Al Viro, fsdevel, linux-kernel
Hi Jan,
On 11/07/2013 07:44 PM, Jan Kara wrote:
> On Tue 05-11-13 18:02:03, Gu Zheng wrote:
>> Stop the loop of iterating bh if we have confirmed page
>> has dirty and writeback buffers.
> Thanks for the patch. What I'm somewhat missing here is a motivation of
> the patch. For the common case where blocksize == pagesize this is a noop
> (only adds some code).
Yes, you're right.
> For the case where blocksize < pagesize we can
> possibly save checking some buffers but how common is that going be?
It's really hard to say.:( But many file systems support small blocksize.
> Does that minimal speed up outweight the cost of additional check / code
> complication?
In fact, without complete test. But I think the speed up can outweigh the cost
if blocksize small enough. For example, blocksize: 1k, pagesize: 4k, we can
reduce 6 bh check(3 dirty, 3 writeback) in the best case.
Best regards,
Gu
>
> Honza
>
>>
>> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
>> ---
>> fs/buffer.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/buffer.c b/fs/buffer.c
>> index 6024877..519cc5c 100644
>> --- a/fs/buffer.c
>> +++ b/fs/buffer.c
>> @@ -112,7 +112,7 @@ void buffer_check_dirty_writeback(struct page *page,
>> *dirty = true;
>>
>> bh = bh->b_this_page;
>> - } while (bh != head);
>> + } while ((bh != head) && !(*writeback && *dirty));
>> }
>> EXPORT_SYMBOL(buffer_check_dirty_writeback);
>>
>> --
>> 1.7.7
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 3+ messages in thread
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