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:
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.