After talking to the kernel developer... https://www.mail-archive.com/linux-block@vger.kernel.org/msg23928.html
The warning is shown because bmap-tools is trying to setup an io sched that is not available on blk-mq. But that is no excuse to be 5-8 times slower. The real culprint was a bug on uas, Fixed with the commit "block: really disable runtime-pm for blk-mq that fix is in: linux-image-4.17.0-3-amd64 4.17.17-1 After installing it. I still get the warning (that needs to be fixed by bmap-tools upstream), but the perfomance is comparable to as it used to be. Thans everyone for you help! On Fri, Aug 17, 2018 at 6:57 PM Ben Hutchings <b...@decadent.org.uk> wrote: > > On Fri, 2018-08-17 at 13:00 +0200, Ricardo Ribalda Delgado wrote: > > Hi Ben > > > > I am experience some very bad performace with SCSI_MQ_DEFAULT, That > > was enabled on Debian 4.17.1 > > > > Please take a look to this > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=906328 > > Talk to the upstream kernel developers (linux-bl...@vger.kernel.org). > > The old block layer is going to be removed in favour of blk-mq > eventually, so I don't see any point in changing the default back. > > Ben. > > -- > Ben Hutchings > It is impossible to make anything foolproof > because fools are so ingenious. > -- Ricardo Ribalda
