On Mon, Sep 4, 2017 at 4:14 PM, Mel Gorman [off-list ref] wrote:

On Thu, Aug 31, 2017 at 03:42:57PM +0100, Mel Gorman wrote:

quoted

On Thu, Aug 31, 2017 at 08:46:28AM +0200, Paolo Valente wrote:

quoted

[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