Open Stack

Hi,

First and foremost, I want to express my heartfelt gratitude for all the
invaluable insights you've provided. I meticulously studied and conducted
numerous tests based on your inputs. While I've managed to implement
certain enhancements, I'd like to delve into those improvements in an
upcoming section. For now, let me address your queries.

Regarding the number of concurrent VMs operating on the OpenStack
hypervisor:

   - Presently, there is a sole VM running on this compute node,
   occasionally there might be two instances. The compute node remains largely
   underutilized, primarily earmarked for my performance assessments. It's
   equipped with a 24-core Intel(R) Xeon(R) Silver 4214 CPU @ 2.20GHz,
   alongside a MemTotal of 48988528 kB. Thus far, I haven't detected any red
   flags. Even during the execution of fio tests within my VMs, there is no
   discernible surge in load.

To @smooney: In relation to ide and virtio, I undertook a secondary test,
meticulously duplicating the attachment methodology, and the outcomes are
akin. Please refer to [1] and [2].

Nevertheless, as per your recommendation, I explored hw_pmu; however, the
outcomes remained consistent. Find the results with hw_pmu disabled in [3],
[4], and [5], and contrasting results with hw_pmu enabled in [6], [7], and
[8].

Nonetheless, I did experience a substantial performance escalation, albeit
solely for a manually attached disk—a comprehensive drive, not the disk
associated with the VM as a singular file [9]. The solitary alteration
involved configuring my cpu_model in nova.conf from IvyBridge to
Cascadelake-Server-noTSX. Even though I achieved approximately 110k iOPS
for the fully attached disk [10], the file-attached disk retained around
19k iOPS [11], with comparable performance evident for the root disk [12].
The latter is also a solitary file, albeit located on a distinct drive of
the same model. For your perusal, I've appended all relevant dumpxml data
[13]. In summation, it seems that the cpu_model significantly influences
performance enhancement, though this effect is not replicated for a "file
disk." The query thus stands: how can we elevate performance for a file
disk?

Might you be willing to share the fio benchmark outcomes from your local
storage configuration? I'm curious to ascertain whether our results align,
or if there's a concealed optimization path I have yet to uncover. I
sincerely appreciate all the assistance you've extended thus far.
/Jan Wasilewski

*References:*
*[1] virtio connected via virsh attach-volume to Openstack instance(<80k
iOPS): https://paste.openstack.org/show/bHqZZWdAwWVYh1rHaIgC/
<https://paste.openstack.org/show/bHqZZWdAwWVYh1rHaIgC/>*
*[2] virtio connected via virsh attach-volume to Openstack instance
dumpxml: https://paste.openstack.org/show/bvEsKiwBd8lL4AUPSOxj/
<https://paste.openstack.org/show/bvEsKiwBd8lL4AUPSOxj/>*
*[3] hw_pmu: False: fio - root disk:
https://paste.openstack.org/show/bAZXQOUrkmVBsJ7yBEql/
<https://paste.openstack.org/show/bAZXQOUrkmVBsJ7yBEql/>*
*[4] hw_pmu: False: fio - attached nvme disk:
https://paste.openstack.org/show/bF1P0qsVG24duuY8F6HV/
<https://paste.openstack.org/show/bF1P0qsVG24duuY8F6HV/>*
*[5] hw_pmu: False: dumpxml:
https://paste.openstack.org/show/b8Yxf5DmPmAxxA070DL1/
<https://paste.openstack.org/show/b8Yxf5DmPmAxxA070DL1/>*
*[6] hw_pmu: True: fio - root disk:
https://paste.openstack.org/show/b7jJ7gR2e9VAAXm1e9PP/
<https://paste.openstack.org/show/b7jJ7gR2e9VAAXm1e9PP/>*
*[7] hw_pmu: True: fio - attached nvme disk(82,5k iOPS) :
https://paste.openstack.org/show/bCrdOnwxrJS6hENxTMK5/
<https://paste.openstack.org/show/bCrdOnwxrJS6hENxTMK5/>*
*[8] hw_pmu: True: dumpxml:
https://paste.openstack.org/show/b8Yxf5DmPmAxxA070DL1/
<https://paste.openstack.org/show/b8Yxf5DmPmAxxA070DL1/>*
*[9] Instruction how to add a "file disk" to kvm instance:
https://www.cyberciti.biz/faq/how-to-add-disk-image-to-kvm-virtual-machine-with-virsh-command/
<https://www.cyberciti.biz/faq/how-to-add-disk-image-to-kvm-virtual-machine-with-virsh-command/>*
*[10] cpu_model: Cascadelake-Server-noTSX fio - attached nvme disk(almost
110k iOPS): https://paste.openstack.org/show/bdKQIgNIH0dy8PLhAIKq/
<https://paste.openstack.org/show/bdKQIgNIH0dy8PLhAIKq/>*
*[11] cpu_model: Cascadelake-Server-noTSX fio - "file disk":
https://paste.openstack.org/show/bjBmPBXi35jWdyJ1cjQt/
<https://paste.openstack.org/show/bjBmPBXi35jWdyJ1cjQt/>*
*[12] cpu_model: Cascadelake-Server-noTSX fio - root disk:
https://paste.openstack.org/show/br49T918vNU5NJXfXYGm/
<https://paste.openstack.org/show/br49T918vNU5NJXfXYGm/>*
*[13] cpu_model: Cascadelake-Server-noTSX dumpxml:
https://paste.openstack.org/show/bns2rWIHCHIWbrR9LUD0/
<https://paste.openstack.org/show/bns2rWIHCHIWbrR9LUD0/>*
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