On 12/19/23 12:06 PM, Matthew Wilcox wrote:
> On Tue, Dec 19, 2023 at 10:42:46AM +0800, Jingbo Xu wrote:
>> } else {
>> bdi->max_ratio = max_ratio;
>> - bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100;
>> + bdi->max_prop_frac = div64_u64(FPROP_FRAC_BASE * max_ratio,
>> + 100 * BDI_RATIO_SCALE);
>> }
>
> Why use div64_u64 here?
>
> FPROP_FRAC_BASE is an unsigned long. max_ratio is an unsigned int, so
> the numerator is an unsigned long. BDI_RATIO_SCALE is 10,000, so the
> numerator is an unsigned int. There's no 64-bit arithmetic needed here.
Yes, div64_u64() is actually not needed here. So it seems
bdi->max_prop_frac = FPROP_FRAC_BASE * max_ratio / 100 / BDI_RATIO_SCALE;
is adequate?
--
Thanks,
Jingbo
