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    SubjectRe: Linux Serial Performance
    "Paul G. Allen" <> writes:

    > I ran some tests on Windows XP and Linux CentOS 5.1 using the Sun
    > NetBeans IDE 6.7.1 profiler. The same Java code on both Linux and XP
    > machines, the same model of machine (Dell, Pentium 4 3GHz, 2.5GB
    > memory). I am using the Sun comm API currently, and previously I was
    > using the Serlio API. In all cases, the profiler shows the serial Tx
    > to be about 20x faster (twenty times) on Windows XP than in Linux. It
    > takes Linux several seconds to Tx 1024 byte blocks of data over the
    > serial port where Windows XP takes a fraction of a second.

    I don't know about Java, but I'm using 460 kb/s and 920 kb/s serial
    ports and Linux can transmit (and receive) full speed data without any
    problem. This includes mobile Pentium III 500 MHz with 460 kb/s NS super
    IO chip.

    4-port OX16PCI954, PL2303 (max 2) and FTDI2232-based USB dongles also
    work as well. I know people use ca. 4 Mb/s async serial (with PPP).

    The last time I remember serial IO problems it was 8-port 8251-based ISA
    card on 486DX. I think it was reliable at max 19200 b/s.

    Perhaps you're requesting hardware (or software) handshaking when it's
    unavailable? Or maybe there is some "padding" configured?

    I wonder what does strace say about it.
    Krzysztof Halasa

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