On 05/10/2026 21.37, Stefano Brivio wrote:
> Bernard, thanks for the investigation and for the patch. Just one doubt:
[...]
> I'm a bit worried we might cause unnecessary setsockopt() calls in some
> corner cases if we go this way, even though it's a rather minor concern
> (we just called splice(), and that setsockopt() is not _that_ expensive
> in comparison).
The 'corked' variable should ensure that we only add the setsockopt when 
it would otherwise add the unneccesary 200ms delay.

I attached the reproducers and benchmarking tools.
The finding from running it was that SPLICE_F_MORE gives plenty extra 
performance even for 8K pipes and setsockopt hardly costs anything.

To test:
# maybe with adjustment to /proc/sys/fs/pipe-user-pages-soft
pasta --config-net -t 127.0.0.1/25432:15432 -- python3 rr.py serve 15432
python3 rr.py 25432


   ┌─────────┬─────────┬───────────────┬─────────────────┬────────────────┐
│  Build  │  Pipes  │ Worst latency │ Upload (Gbit/s) │ Download/Gbit  │
├─────────┼─────────┼───────────────┼─────────────────┼────────────────┤
│ base    │ 8 KiB   │ 208 ms        │ 89–91           │ 87–89          │
├─────────┼─────────┼───────────────┼─────────────────┼────────────────┤
│ patched │ 8 KiB   │ 0.1 ms        │ 88–89           │ 86–89          │
├─────────┼─────────┼───────────────┼─────────────────┼────────────────┤
│ nomore  │ 8 KiB   │ 0.1 ms        │ 42–43           │ 40             │
├─────────┼─────────┼───────────────┼─────────────────┼────────────────┤
│ base    │ default │ 0.3 ms        │ 203–204         │ 189–198        │
├─────────┼─────────┼───────────────┼─────────────────┼────────────────┤
│ patched │ default │ 0.1 ms        │ 203–205         │ 185–190        │
├─────────┼─────────┼───────────────┼─────────────────┼────────────────┤
│ nomore  │ default │ 0.1 ms        │ 193–203         │ 177–190        │
└─────────┴─────────┴───────────────┴─────────────────┴────────────────┘


Ciao
Bernhard M.