Re: [PATCH BUGFIX/IMPROVEMENT V2 0/3] three bfq fixes restoring service guarantees with random sync writes in bg

[Ming Lei]

On Mon, Sep 4, 2017 at 4:14 PM, Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, Aug 31, 2017 at 03:42:57PM +0100, Mel Gorman wrote:
>> On Thu, Aug 31, 2017 at 08:46:28AM +0200, Paolo Valente wrote:
>> > [SECOND TAKE, with just the name of one of the tester fixed]
>> >
>> > Hi,
>> > while testing the read-write unfairness issues reported by Mel, I
>> > found BFQ failing to guarantee good responsiveness against heavy
>> > random sync writes in the background, i.e., multiple writers doing
>> > random writes and systematic fdatasync [1]. The failure was caused by
>> > three related bugs, because of which BFQ failed to guarantee to
>> > high-weight processes the expected fraction of the throughput.
>> >
>>
>> Queued on top of Ming's most recent series even though that's still a work
>> in progress. I should know in a few days how things stand.
>>
>
> The problems with parallel heavy writers seem to have disappeared with this
> series. There are still revisions taking place on Ming's to overall setting
> of legacy vs mq is still a work in progress but this series looks good.

Hi Mel and Paolo,

BTW, no actual functional change in V4.

Also could you guys provide one tested-by since looks you are using
it in your test?

Thanks,
Ming Lei