Re: TSC instead of ACPI: powerd doesn't work anymore (to be expected?)

From: David Xu (davidxu_at_freebsd.org)
Date: 10/31/05

  • Next message: Nate Lawson: "Re: 1kHz noise from C3 sleep" 
    Date: Mon, 31 Oct 2005 08:37:09 +0800
To: "M. Warner Losh" <imp@bsdimp.com>

    M. Warner Losh wrote:

    >Actually, ioport reads can be faster than the 1us that's widely
    >quoted. ioport reads can be as fast as ~125ns (2 cycles at 16MHz).
    >However, experience has shown that they are rarely this fast. I've
    >seen 8MB/s pio over the pci bus on some custom hardware we have, which
    >2Mreads/sec which is about 500ns per read. I think that the pci
    >hardware that I was reading had a few extra wait states...
    >
    >The 1us/read is for devices on the ISA bus or for hardware that
    >emulates this timing.
    >
    >Warner
    >
    >
    >
    >
    The ioport speed is also unstable, on my IBM T43 thinkpad notebook,
    if I load wireless driver, the gettimeofday syscall will be 4 times slower
    than no wireless driver loaded, though I am not using the wireless
    network.

    David Xu

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  • Next message: Nate Lawson: "Re: 1kHz noise from C3 sleep"

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