Re: [PATCH BUGFIX V2] block, bfq: fix operator in BFQQ_TOTALLY_SEEKY
From: Paolo Valente
Date: Mon Jun 24 2019 - 15:18:23 EST
> Il giorno 24 giu 2019, alle ore 18:12, Jens Axboe <axboe@xxxxxxxxx> ha scritto:
> On 6/22/19 2:44 PM, Paolo Valente wrote:
>> By mistake, there is a '&' instead of a '==' in the definition of the
>> macro BFQQ_TOTALLY_SEEKY. This commit replaces the wrong operator with
>> the correct one.
> A bit worrying that this wasn't caught in testing, as it would have
> resulted in _any_ queue being positive for totally seeky?
Fortunately there's a somewhat reassuring explanation. The commit
introducing this macro prevented seeky queues from being considered
soft real-time. And, to be more selective, it actually filtered out
only totally seeky queues, i.e., queues whose last I/O requests are
*all* random. With this error, any seeky queue was considered totally
seeky. This the broke (only) selectivity.
> Anyway, applied.
> Jens Axboe