Zadrot & FrostByte
Zadrot
Hey FrostByte, I was just digging into an algorithm that optimizes resource allocation under constraints—looks like a puzzle we could both crack apart. Got any thoughts?
FrostByte
Sounds like a classic combinatorial optimization, tricky constraints can turn even a clean algorithm into a labyrinth. What constraints are you juggling? Maybe we can spot a hidden symmetry.
Zadrot
I’m looking at three hard constraints: memory is capped at 256 MiB, latency must stay under 50 ms for every request, and the network only supports UDP so I have to rebuild reliability myself. If we can swap the bandwidth‑heavy chunks for compressed, pre‑computed slices, we might break the symmetry. Think you can find a place to shave off those cycles?
FrostByte
Memory caps are the classic “tight‑rope” problem – keep a tight cache of those pre‑computed slices and drop anything you can recompute on the fly. For latency, pipelining the UDP packets and adding a lightweight ACK scheme can shave cycles, just watch the extra round‑trip cost. And compress the heavy chunks with a lossless codec that’s cheap to decompress; a single extra CPU cycle per packet is better than a 30 ms jitter spike. Keep the checksum simple – a 16‑bit CRC is usually enough for UDP and saves cycles compared to a full SHA. That’s the spot where you can trim the cycles, no?
Zadrot
That’s a solid playbook. 256 MiB is a thin line, so keep the cache eviction policy greedy but deterministic—maybe LRU on a per‑chunk basis. 50 ms latency is tight; a lightweight ACK per burst works, but make the ACK piggyback on the next data packet if possible. Lossless codec? Snappy or ZSTD at level 1 will give you a good trade‑off. 16‑bit CRC is enough for most UDP; just double‑check against that one “burst of data that turns into a DNS‑style error” scenario. I’ll tweak the pipeline to see if we can shave another 3–5 ms. Thoughts?
FrostByte
That’s the right vibe—keep the eviction policy tight, so you always know what’s in the cache. Piggybacking the ACK is a neat trick; just make sure the packet size still fits in one UDP datagram. Snappy or ZSTD‑1 will keep decompression cheap; if you hit that DNS‑style error you can fall back to a simple checksum first. A 3–5 ms shave is realistic if you can batch a few more packets before you hit the 50 ms wall. Let me know how the numbers look after the tweak.
Zadrot
Got the stats—average latency is 44 ms, memory usage is 240 MiB, cache hit rate sits at 93 %. One edge case still spikes to 48 ms, but otherwise the tweak holds. Any other bottleneck you want me to flag?
FrostByte
Looks solid—44 ms average and 240 MiB is under the limit. The 48 ms spike is close; keep an eye on bursty traffic that could push the UDP buffer overrun. Also watch for memory fragmentation if you’re allocating many small slices; a simple allocator tweak could keep that 240 MiB consistent. CPU load spikes when recomputing on cache misses—profile that path to make sure you’re not hitting the 50 ms deadline when the miss rate rises. Otherwise, you’ve cornered most of the obvious holes.