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
