Poor Cache Hit Rate with Nydus + Dragonfly

[zf930530]

Bug report:

I’ve noticed that when using Dragonfly to accelerate Nydus images, the cache hit rate is very poor, even after I preheat the images. During my investigation, I found that preheating caches the entire layer as a whole, and the generated taskID metadata does not include the Content-Range. However, when Nydus requests the image, its lazy-load mechanism causes each request to include a Content-Range. In this case, the calculated taskID does not match the preheated taskID, resulting in a cache miss.

What’s worse, even for the same image, the Content-Range in Nydus requests can vary between pulls, which further reduces the cache hit rate. Does the community have any plans to improve this situation? If so, could you share details about the proposed improvements?

Expected behavior:

Improving Cache Hit Rate for Nydus Images.

How to reproduce it:

Each time pulling Nydus images.

Environment:

• Dragonfly version: 2.1.41
• OS: centos 8

[zf930530]

I found this config: prefetch.
However when I set prefetch: true, back source still happened on seed-peer.

[gaius-qi]

Please use rust client with helm chart(v2.1.64).

[zf930530]

Hi,
I conducted tests using version 2.1.64 and converted a total of 8 Nydus images using the nydusify convert command, resulting in a total size of 4768MB. I then used the preheat URL to preheat the images, and observed that the seed-peer had successfully preheated the images.
Finally, when I pulled the images on the peer node, I used the iftop command to monitor the network traffic. I noticed 927MB of traffic from the seed-peer to the Harbor, with no back-to-source traffic on the peer node. Based on this, I calculated that approximately 20% of the traffic originated from the seed-peer's back-to-source actions.
Upon checking the seed-peer logs, I found that all back source headers included the Range header. Is this behavior expected?

[gaius-qi]

@zf930530 How do you preheat? There are differences between the preheating of Nydus image and OCI image.

[zf930530]

curl --location --request POST 'http://dragonfly-manager-url/oapi/v1/jobs' --header 'Content-Type: application/json'
-- header 'Authorization: Bearer xxxxxx'
-- data-raw {
"type": "preheat",
"args": {
"type": "image",
"url": "https://harbor_url/v2/test/alpine/manifests/v1",
"filteredQueryParams": "Expires&Signature",
"username": "xxx",
"password": "xxx"
}
}

[gaius-qi]

@zf930530 Can you provide all of the seed client logs(/var/log/dragonfly/dfdaemon/)?