On Sun, Jun 10, 2012 at 12:36:41PM +0800, Fengguang Wu wrote:
>Wanpeng,
>
>Sorry this I won't take this: it don't really improve anything. Even
>with the changed test, the real intervals are still some random values
>above (and not far away from) 200ms.. We are saying about 200ms
>intervals just for convenience.
>
But some parts like:
__bdi_update_bandwidth which bdi_update_bandwidth will call:
if(elapsed < BANDWIDTH_INTERVAL)
return;
or
global_update_bandwidth:
if(time_before(now, update_time + BANDWIDTH_INTERVAL))
return;
You me just ignore this disunion ?
Regards,
Wanpeng Li
>
>On Sun, Jun 10, 2012 at 12:20:05PM +0800, Wanpeng Li wrote:
>> From: Wanpneg Li <liwp@xxxxxxxxxxxxxxxxxx>
>>
>> Since bdi_update_bandwidth function should estimate write bandwidth at 200ms intervals,
>> so the time is bdi->bw_time_stamp + BANDWIDTH_INTERVAL == jiffies, but
>> if use time_is_after_eq_jiffies intervals will be bdi->bw_time_stamp +
>> BANDWIDTH_INTERVAL + 1.
>>
>> Signed-off-by: Wanpeng Li <liwp@xxxxxxxxxxxxxxxxxx>
>> ---
>> mm/page-writeback.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
>> index c833bf0..099e225 100644
>> --- a/mm/page-writeback.c
>> +++ b/mm/page-writeback.c
>> @@ -1032,7 +1032,7 @@ static void bdi_update_bandwidth(struct backing_dev_info *bdi,
>> unsigned long bdi_dirty,
>> unsigned long start_time)
>> {
>> - if (time_is_after_eq_jiffies(bdi->bw_time_stamp + BANDWIDTH_INTERVAL))
>> + if (time_is_after_jiffies(bdi->bw_time_stamp + BANDWIDTH_INTERVAL))
>> return;
>> spin_lock(&bdi->wb.list_lock);
>> __bdi_update_bandwidth(bdi, thresh, bg_thresh, dirty,
>> --
>> 1.7.9.5
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