Re: [PATCH BUGFIX] block, bfq: lower-bound the estimated peak rate to 1

[Jens Axboe]

On 3/26/18 8:06 AM, Paolo Valente wrote:
> If a storage device handled by BFQ happens to be slower than 7.5 KB/s
> for a certain amount of time (in the order of a second), then the
> estimated peak rate of the device, maintained in BFQ, becomes equal to
> 0. The reason is the limited precision with which the rate is
> represented (details on the range of representable values in the
> comments introduced by this commit). This leads to a division-by-zero
> error where the estimated peak rate is used as divisor. Such a type of
> failure has been reported in [1].
> 
> This commit addresses this issue by:
> 1. Lower-bounding the estimated peak rate to 1
> 2. Adding and improving comments on the range of rates representable

Applied for 4.17, thanks.

-- 
Jens Axboe