On 09/27/2014 12:14 AM, Andras Kovacs wrote:
Hi all, could someone explain to me: - what is the difference between blk-mq and scsi-mq
blk-mq is the actual block layer, while scsi-mq enables the scsi subsystem to use blk-mq. Any driver that wish to use blk-mq, has to explicit hook into it.
- why don't I observe large speedups when running the same tiotests on Linux v3.12 (which has no blk-mq) and Linux v3.14 (which does have blk-mq) on a Xilinx Zynq development board (the two Linux versions are configured by Xilinx Zynq and I know only how to add kernel command line parameters)?
Only the virtio driver (and the null blk driver) have been converted to blk-mq in 3.14.
- when Linux v3.17 becomes available (and Xilinx Zynq ports it for their development board) will I see large speedups reading/writing to the target SDD (which is driven through the UFS driver)?
Depends if you're CPU bound. If you are, then a speedup is expected. You will at least see lower CPU usage.
scsi-mq has to be explicit enabled with the scsi_mod.use_blk_mq=Y in the kernel boot options for 3.17 until it is marked stable.
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