on 6/12/2024 5:52 AM, Andrew Morton wrote:
> On Thu, 6 Jun 2024 11:35:47 +0800 Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> wrote:
>
>> Factor out balance_wb_limits to remove repeated code
>>
>> Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
>> ---
>> mm/page-writeback.c | 25 +++++++++++++++++--------
>> 1 file changed, 17 insertions(+), 8 deletions(-)
>>
>> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
>> index bf050abd9053..f611272d3c5b 100644
>> --- a/mm/page-writeback.c
>> +++ b/mm/page-writeback.c
>> @@ -1783,6 +1783,21 @@ static inline void wb_dirty_exceeded(struct dirty_throttle_control *dtc,
>> ((dtc->dirty > dtc->thresh) || strictlimit);
>> }
>>
>> +/*
>> + * The limits fileds dirty_exceeded and pos_ratio won't be updated if wb is
>> + * in freerun state. Please don't use these invalid fileds in freerun case.
>
> s/fileds/fields/. I queued a fix for this.
Thanks for fixing this.
>
>> + */
>> +static void balance_wb_limits(struct dirty_throttle_control *dtc,
>> + bool strictlimit)
>> +{
>> + wb_dirty_freerun(dtc, strictlimit);
>> + if (dtc->freerun)
>> + return;
>> +
>> + wb_dirty_exceeded(dtc, strictlimit);
>> + wb_position_ratio(dtc);
>> +}
>> +
>> /*
>> * balance_dirty_pages() must be called by processes which are generating dirty
>> * data. It looks at the number of dirty pages in the machine and will force
>> @@ -1869,12 +1884,9 @@ static int balance_dirty_pages(struct bdi_writeback *wb,
>> * Calculate global domain's pos_ratio and select the
>> * global dtc by default.
>> */
>> - wb_dirty_freerun(gdtc, strictlimit);
>> + balance_wb_limits(gdtc, strictlimit);
>> if (gdtc->freerun)
>> goto free_running;
>
> Would it be neater to do
>
> if (balance_wb_limits(...))
> goto free_running;
>
> ?
Here are two reasons why I retrieve freerun info from dtc:
1. Retrieve freerun and other calculated info from balance_domain_limits and
balance_wb_limits in the same way. Personly think it's cleaner.
2. It's more clear that we stop to limit pages because of freerun state of
wb.
>
> That would require a balance_wb_limits() comment update and probably
> name change. Just a thought.
>
>
