Re: [PATCH V1 0/6] fast qom tree get

On 4/28/2025 4:04 AM, Markus Armbruster wrote: > Steven Sistare <steven.sistare(a)oracle.com&gt; writes: > >> On 4/9/2025 3:39 AM, Markus Armbruster wrote: >>> Hi Steve, I apologize for the slow response. >>> >>> Steve Sistare <steven.sistare(a)oracle.com&gt; writes: >>> >>>> Using qom-list and qom-get to get all the nodes and property values in a >>>> QOM tree can take multiple seconds because it requires 1000's of individual >>>> QOM requests. Some managers fetch the entire tree or a large subset >>>> of it when starting a new VM, and this cost is a substantial fraction of >>>> start up time. >>> >>> "Some managers"... could you name one? >> >> My personal experience is with Oracle's OCI, but likely others could benefit. > > Elsewhere in this thread, we examined libvirt's use qom-get. Its use of > qom-get is also noticably slow, and your work could speed it up. > However, most of its use is for working around QMP interface > shortcomings around probing CPU flags. Addressing these would help it > even more. > > This makes me wonder what questions Oracle's OCI answers with the help > of qom-get. Can you briefly describe them? > > Even if OCI would likewise be helped more by better QMP queries, your > fast qom tree get work might still be useful. We already optimized our queries as a first step, but what remains is still significant, which is why I submitted this RFE.