on 11/24/2022 2:09 AM, Tejun Heo wrote:
> On Wed, Nov 23, 2022 at 02:03:52PM +0800, Kemeng Shi wrote:
>> @@ -964,10 +963,8 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
>> unsigned int bio_size = throtl_bio_data_size(bio);
>>
>> /* Charge the bio to the group */
>> - if (!bio_flagged(bio, BIO_BPS_THROTTLED)) {
>> - tg->bytes_disp[rw] += bio_size;
>> - tg->last_bytes_disp[rw] += bio_size;
>> - }
>> + tg->bytes_disp[rw] += bio_size;
>> + tg->last_bytes_disp[rw] += bio_size;
>
> Are you sure this isn't gonna lead to double accounting? IIRC, the primary
> purpose of this flag is avoiding duplicate accounting of bios which end up
> going through the throttling path multiple times for whatever reason and
> we've had numerous breakages around it.
Sorry for the mistake, this change does lead to double accounting.
> To address the problem you're describing in this patch, wouldn't it make
> more sense to set the flag only when the bio traversed the entire tree
> rather than after each tg?
I will address the problem in this way in next version. Thanks for the
advice.
--
Best wishes
Kemeng Shi
