On Sun, 14 Oct 2001, Manfred Spraul wrote: > I've cleaned up the winbond-840 interrupt handler and added a very > simple interrupt avoidance scheme: "Cleaned up"?? Uhmm, that's certainly not cleaner. Also, keep in mind that the winbond-840 driver is a special case. The Tx FIFO limit circuitry is broken on some chips. The driver must explicitly limit how many bytes are permitted into the on-chip FIFO to avoid transmit corruption. > Result: > single stream tcp receive performance up from 9.2 MB/sec to 10.5 MB/sec > (mtu 1500). MTU=1500 at 100Mbps should never be an interesting case. A P5-100 system could handle 2-3 full-rate 100Mbps connections. > In both cases, 0 packet drops (as expected - one tcp streams with a > window of 64 kB and a 64 entry rx queue makes packet drops impossible) > > IMHO that shows that packet drops are not the right sign when to switch > on interrupt mitigation - packets aren't dropped, This should be obvious: making a long Rx ring will prevent packets from being dropped. However that same long Rx will prevent the appropriate packets from being dropped when the system is overloaded. > instead the tcp sender > just sends packets slower and performance goes down. Isn't that the desired effect? Specifically: dropping packets is sometimes the correct way to indicate TCP congestion. Donald Becker becker@scyld.com Scyld Computing Corporation http://www.scyld.com 410 Severn Ave. Suite 210 Second Generation Beowulf Clusters Annapolis MD 21403 410-990-9993 - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
