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    SubjectRe: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3
    On Thu, 22 Feb 2007, Evgeniy Polyakov wrote:

    > > 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.)
    >
    > I tried already :) - I just made a allocations atomic in tcp_sendmsg() and
    > ended up with 1/4 of the sends blocking (I counted both allocation
    > failure and socket queue overflow). Those 20k blocked requests were
    > created in about 20 seconds, so roughly saying we have 1k of thread
    > creation/freeing per second - do we want this?

    A dynamic pool will smooth thread creation/freeing up by a lot.
    And, in my box a *pthread* create/free takes ~10us, at 1000/s is 10ms, 1%.
    Bad, but not so aweful ;)
    Look, I'm *definitely* not trying to advocate the use of async syscalls for
    network here, just pointing out that when we're talking about threads,
    Linux does a pretty good job.




    - Davide


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