Booting 4.17 with the kernel option scsi_mod.use_blk_mq=0 returns the write time to the original 25.8 sec
On Fri, Aug 17, 2018 at 12:15 PM Ricardo Ribalda Delgado <ricardo.riba...@gmail.com> wrote: > > It is a CFast connected via USB3 > > Digging a bit, seems to be related to the module option: > > scsi_mod.use_blk_mq > > which is true on the new kernel and false on the old kernel. > > > On Fri, Aug 17, 2018 at 12:12 PM Simon McVittie <s...@debian.org> wrote: > > > > On Fri, 17 Aug 2018 at 10:27:47 +0200, Ricardo Ribalda Delgado wrote: > > > Current version of bmap on combination with the current debian kernel > > > gives a > > > terrible low performance: > > ... > > > $sudo bmaptool copy image.wic /dev/sdb > > > > What sort of hardware is /dev/sdb? I think recent kernels offer different > > classes of scheduler for (rotating, magnetic) hard disks and for > > solid-state storage, which might explain why you see none instead of noop. > > > > If you copy a raw image to the same device on each kernel (without using > > bmaptool to skip unused blocks), how long does it take with the default > > scheduler, and how long does it take with the noop or none scheduler > > (whichever is available)? > > > > If there has been a general performance regression in the kernel for > > this device type, there is unlikely to be anything that bmaptool can do > > about it, but a refinement of the patch you suggested (checking which > > schedulers are available, and selecting either noop or none, whichever > > is available) would make sense. > > > > smcv > > > > -- > Ricardo Ribalda -- Ricardo Ribalda
