On Thu, Aug 3, 2017 at 5:42 PM, Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote: > On Thu, Aug 03, 2017 at 05:17:21PM +0800, Ming Lei wrote: >> Hi Mel Gorman, >> >> On Thu, Aug 3, 2017 at 4:51 PM, Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote: >> > Hi Christoph, >> > >> > I know the reasons for switching to MQ by default but just be aware that it's >> > not without hazards albeit it the biggest issues I've seen are switching >> > CFQ to BFQ. On my home grid, there is some experimental automatic testing >> > running every few weeks searching for regressions. Yesterday, it noticed >> > that creating some work files for a postgres simulator called pgioperf >> > was 38.33% slower and it auto-bisected to the switch to MQ. This is just >> > linearly writing two files for testing on another benchmark and is not >> > remarkable. The relevant part of the report is >> >> We saw some SCSI-MQ performance issue too, please see if the following >> patchset fixes your issue: >> >> http://marc.info/?l=linux-block&m=150151989915776&w=2 >> > > That series is dealing with problems with legacy-deadline vs mq-none where > as the bulk of the problems reported in this mail are related to > legacy-CFQ vs mq-BFQ. The serials deals with none and all mq schedulers, and you can see the improvement on mq-deadline in cover letter, :-) Thanks, Ming Lei
