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Making Xen's dom0 I/O path NUMA aware

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Re: Making Xen's dom0 I/O path NUMA aware

#5

Post by twoodfin »

This article is a great example of the limits of LLM technical writing.

Say what you will about—or try to prompt out—their rhetorical flourishes, they can link together a series of background, observations, implications, …

But man, they are hopeless at crafting a high-level narrative. It’s one big hedge maze of a garden path:

This part makes good on that - and along the way it covers two things we did not plan to fix. One we hit before the real work could start: dom0's own memory placement was so skewed that synthesising a topology for dom0 without fixing it first would have been an exercise in lying to a kernel that had no memory to back the lie with. That one is a prerequisite, not a detour - everything else in this part is built on top of it. The other we hit after the work was nominally done: a memory-placement bug in our own toolstack that had been silently broken for as long as multi-vnode vNUMA had existed in our tree, and only ever surfaced under a memory-bandwidth benchmark. That one is the genuine detour, and it waits until the end.

Let's start with the prerequisite.

Where are we going here and why?!

Re: Making Xen's dom0 I/O path NUMA aware

#7

Post by actionfromafar »

twoodfin wrote: post #5

This article is a great example of the limits of LLM technical writing. Say what you will about—or try to prompt out—their rhetorical flourishes, they can link together a series of background, observations, implications, … But man, they are hopeless at crafting a high-level narrative. It’s one big hedge maze of a garden path: This part makes good on that - and along the way it covers two things we did not plan to fix…

And what's so tiring is that with humans, there's often (not always) a coherent meaning there to be untangled. With the LLMs, probably not, because if there was, it would have been in the prompt and the rambling wouldn't be as bad.

Re: Making Xen's dom0 I/O path NUMA aware

#9

Post by rickydroll »

unixhero wrote: post #8
tjoff wrote: post #6

Earlier quoted context omitted.

Why is KVM a thing when we have great and free Xen virtualization?

Which hypervisors are free with Xen?

xcp-ng. You can use a built-in mini-management tool (xo-lite) to build the full-featured management tool (Xen Orchestra) from git. There are a couple of maintained scripts that automate the process.

I like it because it is not a bag of parts. Everything is included. It is a VM toolkit that JFW, and it is not what keeps me awake at night

Re: Making Xen's dom0 I/O path NUMA aware

#10

Post by unixhero »

rickydroll wrote: post #9
unixhero wrote: post #8

Earlier quoted context omitted.

Which hypervisors are free with Xen?

xcp-ng. You can use a built-in mini-management tool (xo-lite) to build the full-featured management tool (Xen Orchestra) from git. There are a couple of maintained scripts that automate the process. I like it because it is not a bag of parts. Everything is included. It is a VM toolkit that JFW, and it is not what keeps me awake at night

So I should ditch Proxmox for this?
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