On Thu, Feb 22, 2007 at 01:59:31PM +0100, Ingo Molnar wrote: > > * Evgeniy Polyakov <[EMAIL PROTECTED]> 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.)
At what point are the cachemiss threads destroyed ? In other words how well does this adapt to load variations ? For example, would this 80MB of RAM continue to be locked down even during periods of lighter loads thereafter ? Regards Suparna > > > 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?) > > Ingo -- Suparna Bhattacharya ([EMAIL PROTECTED]) Linux Technology Center IBM Software Lab, India - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/