Gather round the CRT kids it's another story time from old man delni...
Back in the before times, Papa Delni setup an old 486 (actually 386 using a cyrix "486" cpu) as an X terminal. This was a hot setup with an ATI Graphics Wonder, AMD Lance network, 8mb of ram, the whole 9 yards.
Everything worked great except the network was terribly slow. Except when I moved the mouse, then it was nice and normal.
Turned out the network card and mouse were on the same IRQ, or maybe the driver was looking at the wrong IRQ, and the network buffers only got drained when the mouse was wiggled.
I actually used that little nugget of knowing things to know to switch to polled network buffers on a big fat firewall that was running freebsd -- it was constantly under huge load so there was no real advantage to waiting for IRQs.
Oh yes `HZ=4000`, `net.link.ifqmaxlen=200`, `net.isr.dispatch=…`. I don't miss running out of hardware resources that would be a few 100 (or 1000) gates to get right like a nesting, vectored interrupt controller with enough sources and priorities.
Back in the before times, Papa Delni setup an old 486 (actually 386 using a cyrix "486" cpu) as an X terminal. This was a hot setup with an ATI Graphics Wonder, AMD Lance network, 8mb of ram, the whole 9 yards.
Everything worked great except the network was terribly slow. Except when I moved the mouse, then it was nice and normal.
Turned out the network card and mouse were on the same IRQ, or maybe the driver was looking at the wrong IRQ, and the network buffers only got drained when the mouse was wiggled.
I actually used that little nugget of knowing things to know to switch to polled network buffers on a big fat firewall that was running freebsd -- it was constantly under huge load so there was no real advantage to waiting for IRQs.
Don't miss that world at all.