4 ms·

John Nagle has posted insightful comments about the historical background for this many times, for example https://news.ycombinator.com/item?id=9048947 https://

John Nagle has posted insightful comments about the historical background for this many times, for example https://news.ycombinator.com/item?id=9048947 https://news.ycombinator.com/item?id=9048947 referenced in the article. He's a prolific HN commenter (#11 on the leaderboard) so it can be hard to find everything, but some more comments searchable via https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=%22delayed%20ack%22%20%22animats%22&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que... or https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=%22tcp_nodelay%22%20%22animats%22&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

Animats 2y ago
The sending pattern matters. Send/Receive/Send/Receive won't trigger the problem, because the request will go out immediately and the reply will provide an ACK and allow another request. Bulk transfers won't cause the problem, because if you fill the outgoing block size, there's no delay. But Send/Send/Receive will. This comes up a lot in game systems, where most of the traffic is small events going one way.
- pipe01 2y ago
  I would imagine that games that require exotic sending patterns would use UDP, giving them more control over the protocol
  - codr7 2y ago
    Size prefixed messages are pretty common, perfectly possible to perform as one send but takes more work.
EvanAnderson 2y ago
I love it when Nagle's algorithm comes up on HN. Inevitably someone, not knowing "Animats" is John Nagle, responds a comment from Animats with a "knowing better" tone. >smile< (I also really like Animats' comments, too.)
- geoelectric 2y ago
  I have to confess that when I saw this post, I quickly skimmed the threads to check if someone was trying to educate Animats on TCP. Think I've only seen that happen in the wild once or twice, but it absolutely made my day when it did.
  - ryandrake 2y ago
    It's always the highlight of my day when it happens, almost as nice as when someone chimes in to educate John Carmack on 3D graphics and VR technology.
    - deleted 2y ago
      [deleted]
- userbinator 2y ago
  I always check if the man himself makes an appearance every time I see that. He has posted a few comments in here already.
- jeltz 2y ago
  It is like when someone here accused Andres Freund (PostgreSQL core dev who recently became famous due to the xz backdoor) of Dunning–Kruger when he had commented on something related to PostgreSQL's architecture which he had spent many many hours working on personally (I think it was pluggable storage). Maybe you just tried to educate the leading expert in the world on his own expertise. :D
SushiHippie 2y ago
FYI the best way to filter by author is 'author:Animats' this will only show results from the user Animats and won't match animats inside the comment text. https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=%22delayed%20ack%22%20author%3AAnimats&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

Animats 2y ago

The sending pattern matters. Send/Receive/Send/Receive won't trigger the problem, because the request will go out immediately and the reply will provide an ACK and allow another request. Bulk transfers won't cause the problem, because if you fill the outgoing block size, there's no delay. But Send/Send/Receive will. This comes up a lot in game systems, where most of the traffic is small events going one way.

pipe01 2y ago
I would imagine that games that require exotic sending patterns would use UDP, giving them more control over the protocol
- codr7 2y ago
  Size prefixed messages are pretty common, perfectly possible to perform as one send but takes more work.

EvanAnderson 2y ago

I love it when Nagle's algorithm comes up on HN. Inevitably someone, not knowing "Animats" is John Nagle, responds a comment from Animats with a "knowing better" tone. >smile< (I also really like Animats' comments, too.)

geoelectric 2y ago
I have to confess that when I saw this post, I quickly skimmed the threads to check if someone was trying to educate Animats on TCP. Think I've only seen that happen in the wild once or twice, but it absolutely made my day when it did.
- ryandrake 2y ago
  It's always the highlight of my day when it happens, almost as nice as when someone chimes in to educate John Carmack on 3D graphics and VR technology.
  - deleted 2y ago
    [deleted]
userbinator 2y ago
I always check if the man himself makes an appearance every time I see that. He has posted a few comments in here already.
jeltz 2y ago
It is like when someone here accused Andres Freund (PostgreSQL core dev who recently became famous due to the xz backdoor) of Dunning–Kruger when he had commented on something related to PostgreSQL's architecture which he had spent many many hours working on personally (I think it was pluggable storage). Maybe you just tried to educate the leading expert in the world on his own expertise. :D

SushiHippie 2y ago

FYI the best way to filter by author is 'author:Animats' this will only show results from the user Animats and won't match animats inside the comment text. https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=%22delayed%20ack%22%20author%3AAnimats&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...