[SOLVED] kvm read ceph single thread limit ?

[gz_jax]

Hello :
I recently encountered a problem with random read iops when performing performance tests.
The scene I built is: pve5.4 + ceph 12.2.12
3 hosts, each host 1ssd + 3hdd (ssd is used for db and wal, hdd is osd)
KVM's disk will enable cache = write back mode, and select VirtIO SCSI single
Zh
Delay in testing random reads, iodeph = 1, numjobs = 1, the average read iops is 200+
As shown below:


Delay in testing random reads, iodeph = 2, numjobs = 1, average read iops is 500+
As shown below:


Delay in testing random reads, iodeph = 1, numjobs = 2, the average read iops is 500+
As shown below:


After testing, it is found that single io and single-threaded iops are fixed at a certain value. Is this normal? If it is not normal, how to adjust it to improve it? For example, adjusting the kvm configuration, the operating system or ceph itself?

thank a lot!

 

[Alwin]

The scene I built is: pve5.4 + ceph 12.2.12

Please upgrade, Proxmox VE 5.4 and Ceph Luminous will go EoL soon.
https://pve.proxmox.com/wiki/FAQ

After testing, it is found that single io and single-threaded iops are fixed at a certain value. Is this normal? If it is not normal, how to adjust it to improve it? For example, adjusting the kvm configuration, the operating system or ceph itself?

Please describe your setup in detail. How do the complete test results look like? And did you test Ceph itself, rados bench?

 

[gz_jax]

Please upgrade, Proxmox VE 5.4 and Ceph Luminous will go EoL soon.
https://pve.proxmox.com/wiki/FAQ


Please describe your setup in detail. How do the complete test results look like? And did you test Ceph itself, rados bench?

Thanks, we found the problem ourselves

 

[Alwin]

Thanks, we found the problem ourselves

And what was it? Maybe others run into this as well.

 

[gz_jax]

And what was it? Maybe others run into this as well.

It ’s actually a misunderstanding, because it is found that the HDD disk is used, which is the case for random read performance