Messages in this thread | | | Subject | Re: Signal driven IO | Date | Wed, 17 Nov 1999 00:24:37 +0000 (GMT) | From | Alan Cox <> |
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> > Benchmark it for your application. For web and ftp traffic the I/O signals > > are a clear winner. > > A clear winner regardless of how many file desciptors are ready per "loop > pass"? Surely there has to be some number at which poll becomes superior. > Certainly with artificial cases where you overload the CPU and deliberately > hit multiple links at the same time.
Web traffic is very large numbers of slow operations. Your ration of busy/queued is low. I'd agree there should be a point where you have a lot of busy operations but web/ftp isnt it.
On a T1 you can expect to see 600 parallel connections. Each is averaging 2 or 3 K a second with a typical 1500 byte MTU. So each FD wakes one or two times a second.
So we have 1200 wakeup events per second over 600 handles. Even at 100polls/sec that means we get 12 positive handles and 588 overheads per poll. As it rises to the real world values its hits 1 and 599 overhead at 1000 polls/sec
Alan
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