Thread (6 messages) 6 messages, 2 authors, 2021-05-03

Re: [PATCH net-next] Reduce IP_FRAG_TIME fragment-reassembly timeout to 1s, from 30s

From: Matt Corallo <hidden>
Date: 2021-05-03 14:30:43

Possibly related (same subject, not in this thread)

At the risk of being obnoxious here - that's a "no" to reconsidering the tradeoffs picked 20 years ago?

I don't want to waste time if the answer is a complete "no", but if it isn't I'm happy to try to figure out what exactly 
the right tradeoffs are here, and spend time implementing things.

Thanks,
Matt

On 4/30/21 14:04, Matt Corallo wrote:
On 4/30/21 13:53, Matt Corallo wrote:
quoted
Buffer bloat exists, but so do networks that will happily drop 1Mbps of packets. The first has always been true, the 
second only more recently has become more and more common (both due to network speed and application behavior).
It may be worth noting, to further highlight the tradeoffs made here - that, given a constant amount of memory allocated 
for fragment reassembly, *under* estimating the timeout will result in only loss of some % of packets which were 
reordered in excess of the timeout, whereas *over* estimating the timeout results in complete blackhole for up to the 
timeout in the face of material packet loss.

This asymmetry is why I suggested possibly random eviction could be useful as a different set of trade-offs, but I'm 
certainly not qualified to make that determination.

Thanks again for your time and consideration,
Matt
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