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    SubjectRe: [PATCH v9 net-next 5/7] net: simple poll/select low latency socket poll
    On 05/06/2013 18:20, Eric Dumazet wrote:
    > On Wed, 2013-06-05 at 16:41 +0300, Eliezer Tamir wrote:
    >> On 05/06/2013 16:30, Eric Dumazet wrote:
    >
    >>> I am a bit uneasy with this one, because an applicatio polling() on one
    >>> thousand file descriptors using select()/poll(), will call sk_poll_ll()
    >>> one thousand times.
    >>
    >> But we call sk_poll_ll() with nonblock set, so it will only test once
    >> for each socket and not loop.
    >>
    >> I think this is not as bad as it sounds.
    >> We still honor the time limit on how long to poll.
    >
    > We still call ndo_ll_poll() a thousand times, and probably do a
    > spinlock/unlock a thousand times in the driver.
    >
    > I would definitely be convinced if you give us some performance numbers
    > of a poll() on a thousand tcp sockets for example.

    So with 1000 sockets this is defiantly not a win
    sockperf with 1000 udp sockets

    sysctl 50 0
    select 178.5 us / 130.0 us
    poll 188.6 us / 130.0 us



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