[PATCH for linux-next] mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately

[PATCH for linux-next] mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately

[Yafang Shao]

This patch is the followup of the prvious patch:
[writeback: schedule periodic writeback with sysctl].

There's another issue to fix.
For example,
- When the tunable was set to one hour and is reset to one second, the
  new setting will not take effect for up to one hour.

Kicking the flusher threads immediately fixes it.

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 mm/page-writeback.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3969e69..768fe4e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1978,7 +1978,16 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
 	int ret;
 
 	ret = proc_dointvec(table, write, buffer, length, ppos);
-	if (!ret && !old_interval && dirty_writeback_interval)
+
+	/*
+	 * Writing 0 to dirty_writeback_interval will disable periodic writeback
+	 * and a different non-zero value will wakeup the writeback threads.
+	 * wb_wakeup_delayed() would be more appropriate, but it's a pain to
+	 * iterate over all bdis and wbs.
+	 * The reason we do this is to make the change take effect immediately.
+	 */
+	if (!ret && write && dirty_writeback_interval &&
+		dirty_writeback_interval != old_interval)
 		wakeup_flusher_threads(WB_REASON_PERIODIC);
 
 	return ret;
-- 
1.8.3.1

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Re: [PATCH for linux-next] mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately

[Jens Axboe]

On 10/14/2017 02:38 AM, Yafang Shao wrote:
> This patch is the followup of the prvious patch:
> [writeback: schedule periodic writeback with sysctl].
> 
> There's another issue to fix.
> For example,
> - When the tunable was set to one hour and is reset to one second, the
>   new setting will not take effect for up to one hour.
> 
> Kicking the flusher threads immediately fixes it.

Queued up, thanks.

-- 
Jens Axboe

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Re: [PATCH for linux-next] mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately

[Damian Tometzki]

On Sat, 14. Oct 16:38, Yafang Shao wrote:
> This patch is the followup of the prvious patch:
> [writeback: schedule periodic writeback with sysctl].
> 
> There's another issue to fix.
> For example,
> - When the tunable was set to one hour and is reset to one second, the
>   new setting will not take effect for up to one hour.
> 
> Kicking the flusher threads immediately fixes it.
> 
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> ---
>  mm/page-writeback.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 3969e69..768fe4e 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -1978,7 +1978,16 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
>  	int ret;
>  
>  	ret = proc_dointvec(table, write, buffer, length, ppos);
> -	if (!ret && !old_interval && dirty_writeback_interval)
> +
> +	/*
> +	 * Writing 0 to dirty_writeback_interval will disable periodic writeback
> +	 * and a different non-zero value will wakeup the writeback threads.
> +	 * wb_wakeup_delayed() would be more appropriate, but it's a pain to
> +	 * iterate over all bdis and wbs.
> +	 * The reason we do this is to make the change take effect immediately.
> +	 */
> +	if (!ret && write && dirty_writeback_interval &&
> +		dirty_writeback_interval != old_interval)
>  		wakeup_flusher_threads(WB_REASON_PERIODIC);
Is that call right ? The call need two arguments ?
--> wakeup_flusher_threads(0,WB_REASON_PERIODIC);

best regards
Damian

>  
>  	return ret;
> -- 
> 1.8.3.1
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
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Re: [PATCH for linux-next] mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately

[Jens Axboe]

On 10/14/2017 11:59 AM, Damian Tometzki wrote:
> On Sat, 14. Oct 16:38, Yafang Shao wrote:
>> This patch is the followup of the prvious patch:
>> [writeback: schedule periodic writeback with sysctl].
>>
>> There's another issue to fix.
>> For example,
>> - When the tunable was set to one hour and is reset to one second, the
>>   new setting will not take effect for up to one hour.
>>
>> Kicking the flusher threads immediately fixes it.
>>
>> Cc: Jens Axboe <axboe@kernel.dk>
>> Cc: Jan Kara <jack@suse.cz>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
>> ---
>>  mm/page-writeback.c | 11 ++++++++++-
>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
>> index 3969e69..768fe4e 100644
>> --- a/mm/page-writeback.c
>> +++ b/mm/page-writeback.c
>> @@ -1978,7 +1978,16 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
>>  	int ret;
>>  
>>  	ret = proc_dointvec(table, write, buffer, length, ppos);
>> -	if (!ret && !old_interval && dirty_writeback_interval)
>> +
>> +	/*
>> +	 * Writing 0 to dirty_writeback_interval will disable periodic writeback
>> +	 * and a different non-zero value will wakeup the writeback threads.
>> +	 * wb_wakeup_delayed() would be more appropriate, but it's a pain to
>> +	 * iterate over all bdis and wbs.
>> +	 * The reason we do this is to make the change take effect immediately.
>> +	 */
>> +	if (!ret && write && dirty_writeback_interval &&
>> +		dirty_writeback_interval != old_interval)
>>  		wakeup_flusher_threads(WB_REASON_PERIODIC);
> Is that call right ? The call need two arguments ?
> --> wakeup_flusher_threads(0,WB_REASON_PERIODIC);

It's right, the nr_pages argument was killed.

-- 
Jens Axboe

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