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    SubjectRe: Linux 2.6.29
    Mark Lord wrote:
    > Lennart Sorensen wrote:
    >>
    >> Well the system is setup like this:
    >>
    >> Core 2 Quad Q6600 CPU (2.4GHz quad core).
    >> Asus P5K mainboard (Intel P35 chipset)
    >> 6GB of ram
    >> PVR500 dual NTSC tuner pci card
    > ..
    >> So the behaviour with cfq is:
    >> Disk light seems to be constantly on if there is any disk activity.
    >> iotop
    >> can show a total io of maybe 1MB/s and the disk light is on constantly.
    > ..
    >
    > Lennart,
    >
    > I wonder if the problem with your system is really a Myth/driver issue?
    >
    > Curiously, I have a HVR-1600 card here, and when recording analog TV with
    > it the disk lights are on constantly. The problem with it turns out to
    > be mythbackend doing fsync() calls ten times a second.
    >
    > My other tuner cards don't have this problem.
    >
    > So perhaps the PVR-500 triggers the same buggy behaviour as the HVR-1600?
    > To work around it here, I decided to use a preload library that replaces
    > the frequent fsync() calls with a more moderated behaviour:
    >
    > http://rtr.ca/hvr1600/libfsync.tar.gz
    >
    > Grab that file and try it out. Instructions are included within.
    > Report back again and let us know if it makes any difference.
    >
    > Someday I may try and chase down the exact bug that causes mythbackend
    > to go fsyncing berserk like that, but for now this workaround is fine.

    mythtv/libs/libmythtv/ThreadedFileWriter.cpp is a good place to start
    (Sync method... uses fdatasync if available, fsync if not).

    mythtv is definitely a candidate for sync_file_range() style output, IMO.

    Jeff




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