Disabling multiqueue I/O schedulers using a kernel parameter is not working in debian11

[Malathi]

Hi,
Since from kernel version 5.0 onwards multiqueue I/O scheduling is enabled by default.
We wanted to disable it in our environment using the below kernel parameter:
scsi_mod.use_blk_mq=0

Seems it doesn't work as expected.Please refer screenshot for more details

Screenshot from 2021-12-21 17-30-48.png (74.82 KiB) Viewed 9324 times

Any help would be appreciated

Thanks in advance

[Bloom]

As root:

Code: Select all

echo none >/sys/block/sda/queue/scheduler

You need to repeat that every time you reboot the system. So you can put this in something like /etc/rc.local or use a kernel parameter:

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GRUB_CMDLINE_LINUX="elevator=noop"

in /etc/default/grub
Add the command to the GRUB_CMDLINE_LINUX line which has other parameters and values and do not copy and paste what you see above.

[sunrat]

Please post terminal output as text in CODE tags rather than a huge image.

[CwF]

You need to repeat that every time you reboot the system. So you can put this in something like /etc/rc.local or use a kernel parameter:

Should be able to use /etc/sysfs.d/ or /etc/sysfs.conf.

[Malathi]

Thanks for the response.

Have read something like below in an article for HDD

"Avoid using the none/noop I/O schedulers for a HDD as sorting requests on block addresses reduce the seek time latencies and neither of these I/O schedulers support this feature."

As we are using HDD, tried to disable and fall back to the non-multiqueue I/O schedulers using a kernel parameter "scsi_mod.use_blk_mq=0"
The output should be "deadline none" . But it doesn't working in Debian11

Any idea why this parameter is not working as expected in Debian11?

[Bloom]

Not every hardware supports every type of scheduler. Your screenshot shows mq-deadline as the default and none as the only two available options. Choose none for usb-media or ssd and mq-deadline for hard disks.

[p.H]

Any idea why this parameter is not working as expected in Debian11?

AFAICS, the module scsi_mod in Debian kernel 5.10 does not support the parameter use_blk_mq any more. You can check with

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modinfo -p scsi_mod

Should be able to use /etc/sysfs.d/ or /etc/sysfs.conf.

This requires package sysfsutils, not sure it is installed by default.

Or one may use a udev rule triggered when the drive is added. Something like

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ACTION=="add", KERNEL=="sda", ATTR{queue/scheduler}="none"

(not tested)