Re: tcp_splice SO_RCVLOWAT code; never invoked?

On Fri, 11 Apr 2025 08:13:23 +0200 Stefano Brivio wrote:

On Fri, 11 Apr 2025 14:54:50 +1000 David Gibson wrote:

...

Hi Stefano,

When debugging the splice EINTR bug I fixed the other day, I found the whole tcp_splice_sock_handler() pretty confusing to follow. So, I was working on some cleanups. But then I noticed something more specifically odd here.

We've discussed the use of SO_RCVLOWAT previously. AIUI, you found it essential to achieve reasonable throughput and load for spliced connections.

From my tests back then (never on what I ended up committing, it seems) it wasn't needed in general, it helped only with bulk transfers that never feel the pipe for some reason. With iperf3, I needed to play with

fill, of course -- Stefano