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    SubjectRe: [PATCH] CPU time clock support in clock_* syscalls
    On Tue, 5 Oct 2004, Roland McGrath wrote:

    > > I just reviewed the code and to my surprise the simple things like
    > >
    > > clock_gettime(CLOCK_PROCESS_CPUTIME_ID) and
    > > clock_gettime(CLOCK_THREAD_CPUTIME_ID) are not supported.
    >
    > You seem to be confused. A clockid_t for a CPU clock encodes a PID, which
    > can be zero to indicate the current thread or current process.

    Is there a standard for that? Or is it an opaque type that you have
    defined this way?

    > > The thread specific time measurements have nothing to do with the posix
    > > standard and may best be kept separate.
    >
    > Nonsense. POSIX defines the notion of CPU clocks for these calls, and that
    > is what I have implemented.

    Posix only defines a process and a thread clock. This is much more.

    > Of course glibc is in charge of what the meaning of the POSIX APIs is.
    > That is true for every call.

    The proper information to realize these clocks is only available on the
    kernel level. A clean API for that would remove lots of code that
    currently exists in glibc.

    I wonder how glibc will realize access to special timer hardware. Will
    glibc be able load device drivers for timer chips?

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