Jeff Garzik wrote:
Do you want to individually send 4000 - 16000 (or more) TX stop /
start events per second to userspace? :) At some point Heisenburg
defeats low latency :)
How about looking at 1000 byte packet transmit example. A gigabit
adapter would send 125,000 packets per second. I'm thinking that most
of the time, you will have enough available buffers in the adapter that
you don't start to see the adapter buffers completely fill up. Are you
saying that 3.2% - 12.8% of the time in this case you're disabling the
tcp/ip stack because the transmit buffers on your card are completely
full? Perhaps with zero copy enabled, but the tcp/ip cpu load alone
will throttle your ability to fill the adapter buffers up.
What does your own experience indicate for gigabit adapter cards?
I could see the buffers backing up for 10/100 cards. So that case
favors your point. I'm still thinking that it's a sign someone should
be buying a 2nd card and ramping up their network capability. But I can
see your point.
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