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    SubjectRe: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.30-2

    On Wed, 1 Dec 2004, Ingo Molnar wrote:

    >
    > * Paul Davis <paul@linuxaudiosystems.com> wrote:
    >
    > > >also, the problem is that jackd uses _named_ fifos, which are tied to
    > > >the raw FS and might trigger journalling activities. Normal pipes
    > > >(unnamed fifos) would not cause such problems. Would it be possible to
    > > >change jackd to use a pair of pipes, instead of a fifo?
    > >
    > > i.e. pipe(2) rather than mkfifo(2) ?
    > >
    > > it would be a complete pain because the pipes have to be
    > > "discoverable" across processes. we would have to do fd passing, which
    > > is still really quite ugly in linux (and other *nix systems). it would
    > > quite difficult, though not impossible.
    >
    > yeah. And i think mkfifo(2) objects ought to behave atomically as well,
    > it's an unfortunate side-effect of atime/mtime inode semantics that they
    > can block.
    >
    > your point is correct, the best way to have a system-wide namespace for
    > synchronization objects is ... the filesystem hierarchy. If you create a
    > unix domain socket then you can distribute your pipe fds, but that's
    > indeed somewhat painful.
    >

    Don't worry about setting up the stuff. Once you have the pipe it ought to
    be RT in the usage of read/write, but setting it up is something you is
    something you do "under boot", just as allocating memory and other
    non-real-time stuff.


    > Ingo
    >

    Esben

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