Messages in this thread |  | | Date | Thu, 22 Feb 2007 13:59:31 +0100 | From | Ingo Molnar <> | Subject | Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3 |
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* Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:
> It is not a TUX anymore - you had 1024 threads, and all of them will > be consumed by tcp_sendmsg() for slow clients - rescheduling will kill > a machine.
maybe it will, maybe it wont. Lets try? There is no true difference between having a 'request structure' that represents the current state of the HTTP connection plus a statemachine that moves that request between various queues, and a 'kernel stack' that goes in and out of runnable state and carries its processing state in its stack - other than the amount of RAM they take. (the kernel stack is 4K at a minimum - so with a million outstanding requests they would use up 4 GB of RAM. With 20k outstanding requests it's 80 MB of RAM - that's acceptable.)
> My tests show that with 4k connections per second (8k concurrency) > more than 20k connections of 80k total block in tcp_sendmsg() over > gigabit lan between quite fast machines.
yeah. Note that you can have a million sleeping threads if you want, the scheduler wont care. What matters more is the amount of true concurrency that is present at any given time. But yes, i agree that overscheduling can be a problem.
btw., what is the measurement utility you are using with kevents ('ab' perhaps, with a high -c concurrency count?), and which webserver are you using? (light-httpd?)
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