Re: Add pselect, ppoll system calls.

From: David Woodhouse (dwmw2_at_infradead.org)
Date: 06/13/05

  • Next message: Jean Delvare: "Re: [PATCH] Adds support for TEA5767 chipset on V4L" 
    To: Ulrich Drepper <drepper@redhat.com>
Date:	Mon, 13 Jun 2005 17:29:37 +0100

    On Mon, 2005-06-13 at 09:10 -0700, Ulrich Drepper wrote:
    > poll()'s timeout value is measrued in milliseconds. Using a 32bit
    > value, as implied by using 'int' for the type, limits the mximum
    > timeout to be 2^31-1 milliseconds, which means about 24 days.

    Ah, OK. I thought you were talking about the timespec in pselect(),
    because that's what you quoted.

    Yes, we should make the time for ppoll() a 64-bit value, so you can
    request a time period longer than 24 days. Shall we also switch to
    microseconds?

    > Believe it or not, people are complaining about this. Changing the
    > timeout to a 64bit millisecond timeout would lift the limitation from
    > the API's POV. I don't know what limitations exist in the kernel
    > itself.

    Indeed. The ABI will be set in stone, but we have some leeway to fix the
    implementation details of the kernel's limitations -- such as the fact
    that on a 32-bit box with HZ == 1000, any requested timeout above
    MAX_LONG milliseconds (24 days) will actually end up being infinite. 

    -- 
dwmw2
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