Re: [PATCH] blk-throttle: Calculate allowed value only when the throttle is enabled

[Oleg Nesterov]

On 10/08, Yu Kuai wrote:
>
> >>  static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long
> >>jiffy_elapsed)
> >>  {
> >>+       if (jiffy_elapsed > HZ &&
> >>+           bps_limit > mul_u64_u64_div_u64(U64_MAX, (u64)HZ,
> >>(u64)jiffy_elapsed);
> >>+               return U64_MAX;
> >>+
> >
> >I can't suggest anything better...
> >
> >but I do not know if it is possible that HZ > jiffy_elapsed. If yes, then
> >mul_u64_u64_div_u64() above is not safe too.
>
> Well, 'jiffy_elapsed > HZ' is judged before mul_u64_u64_div_u64().

Yes, sorry, somehow I didn't notice this check.

Oleg.