I can reproduce with qemu:
# ls /sys/block/nvme*n1/mq/*/cpu_list
/sys/block/nvme0n1/mq/0/cpu_list
/sys/block/nvme0n1/mq/1/cpu_list
/sys/block/nvme0n1/mq/2/cpu_list
/sys/block/nvme0n1/mq/3/cpu_list
/sys/block/nvme0n1/mq/4/cpu_list
/sys/block/nvme0n1/mq/5/cpu_list
/sys/block/nvme0n1/mq/6/cpu_list
Here is the qemu cmdline emulating 8-queue nvme while the VM has 12 cpu:
# qemu-system-x86_64 -m 4096 -smp 12 \
-kernel /path-to-kernel/linux-4.18.10/arch/x86_64/boot/bzImage \
-hda /path-to-img/ubuntu1804.qcow2 \
-append "root=/dev/sda1 init=/sbin/init text" -enable-kvm \
-net nic -net user,hostfwd=tcp::5022-:22 \
-device nvme,drive=nvme1,serial=deadbeaf1,num_queues=8 \
-drive file=/path-to-img/nvme.disk,if=none,id=nvme1
Dongli Zhang
On 10/08/2018 01:05 PM, Prasun Ratn wrote:
> Hi
>
> I have an NVMe SSD that has 8 hw queues and on older kernels I see all
> 8 show up. However on a recent kernel (I tried 4.18), I only see 7. Is
> this a known issue?
>
> $ uname -r
> 4.14.1-1.el7.elrepo.x86_64
>
> $ ls /sys/block/nvme*n1/mq/*/cpu_list
> /sys/block/nvme0n1/mq/0/cpu_list
> /sys/block/nvme0n1/mq/1/cpu_list
> /sys/block/nvme0n1/mq/2/cpu_list
> /sys/block/nvme0n1/mq/3/cpu_list
> /sys/block/nvme0n1/mq/4/cpu_list
> /sys/block/nvme0n1/mq/5/cpu_list
> /sys/block/nvme0n1/mq/6/cpu_list
> /sys/block/nvme0n1/mq/7/cpu_list
> /sys/block/nvme1n1/mq/0/cpu_list
> /sys/block/nvme1n1/mq/1/cpu_list
> /sys/block/nvme1n1/mq/2/cpu_list
> /sys/block/nvme1n1/mq/3/cpu_list
> /sys/block/nvme1n1/mq/4/cpu_list
> /sys/block/nvme1n1/mq/5/cpu_list
> /sys/block/nvme1n1/mq/6/cpu_list
> /sys/block/nvme1n1/mq/7/cpu_list
> /sys/block/nvme2n1/mq/0/cpu_list
> /sys/block/nvme2n1/mq/1/cpu_list
> /sys/block/nvme2n1/mq/2/cpu_list
> /sys/block/nvme2n1/mq/3/cpu_list
> /sys/block/nvme2n1/mq/4/cpu_list
> /sys/block/nvme2n1/mq/5/cpu_list
> /sys/block/nvme2n1/mq/6/cpu_list
> /sys/block/nvme2n1/mq/7/cpu_list
> /sys/block/nvme3n1/mq/0/cpu_list
> /sys/block/nvme3n1/mq/1/cpu_list
> /sys/block/nvme3n1/mq/2/cpu_list
> /sys/block/nvme3n1/mq/3/cpu_list
> /sys/block/nvme3n1/mq/4/cpu_list
> /sys/block/nvme3n1/mq/5/cpu_list
> /sys/block/nvme3n1/mq/6/cpu_list
> /sys/block/nvme3n1/mq/7/cpu_list
>
>
> $ uname -r
> 4.18.10-1.el7.elrepo.x86_64
>
> $ ls /sys/block/nvme*n1/mq/*/cpu_list
> /sys/block/nvme0n1/mq/0/cpu_list
> /sys/block/nvme0n1/mq/1/cpu_list
> /sys/block/nvme0n1/mq/2/cpu_list
> /sys/block/nvme0n1/mq/3/cpu_list
> /sys/block/nvme0n1/mq/4/cpu_list
> /sys/block/nvme0n1/mq/5/cpu_list
> /sys/block/nvme0n1/mq/6/cpu_list
> /sys/block/nvme1n1/mq/0/cpu_list
> /sys/block/nvme1n1/mq/1/cpu_list
> /sys/block/nvme1n1/mq/2/cpu_list
> /sys/block/nvme1n1/mq/3/cpu_list
> /sys/block/nvme1n1/mq/4/cpu_list
> /sys/block/nvme1n1/mq/5/cpu_list
> /sys/block/nvme1n1/mq/6/cpu_list
> /sys/block/nvme2n1/mq/0/cpu_list
> /sys/block/nvme2n1/mq/1/cpu_list
> /sys/block/nvme2n1/mq/2/cpu_list
> /sys/block/nvme2n1/mq/3/cpu_list
> /sys/block/nvme2n1/mq/4/cpu_list
> /sys/block/nvme2n1/mq/5/cpu_list
> /sys/block/nvme2n1/mq/6/cpu_list
> /sys/block/nvme3n1/mq/0/cpu_list
> /sys/block/nvme3n1/mq/1/cpu_list
> /sys/block/nvme3n1/mq/2/cpu_list
> /sys/block/nvme3n1/mq/3/cpu_list
> /sys/block/nvme3n1/mq/4/cpu_list
> /sys/block/nvme3n1/mq/5/cpu_list
> /sys/block/nvme3n1/mq/6/cpu_list
>
