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    SubjectRe: Ctrl+C doesn't interrupt process waiting for I/O
    Török Edwin wrote:
    > Hi,
    >
    > I have encountered the following situation several times, but I've been
    > unable to come up with a way to reproduce this until now:
    > - some process is keeping the disk busy (some cron job for example:
    > updatedb, chkrootkit, ...)
    > - other processes that want to do I/O have to wait (this is normal)
    > - I have a (I/O bound) process running in my terminal, and I want to
    > interrupt it with Ctrl+C
    > - I type Ctrl+C several times, and the process is not interrupted for
    > several seconds (10-30 secs)
    > - if I type Ctrl+Z, and use kill %1 the process dies faster than
    > waiting for it to react to Ctrl+C
    >
    > This issue occurs both on my x86-64 machine that uses reiserfs, and on
    > my x86 machine that uses XFS, so it doesn't seem related to the
    > underlying FS.
    > I use 2.6.25-2 and 2.6.26-rc8 now; I don't recall seeing this behaviour
    > with old kernels (IIRC I see this since 2.6.21 or 2.6.23).
    >
    > Is this intended behaviour, or should I report a bug?
    >

    Yes, it's intended behaviour. Filesystem IO syscalls are considered
    "fast" and are interruptible. Usermode code can reasonably expect that
    file IO will never return EINTR.

    That said, if a program is blocking for tens of seconds in block IO,
    then that could be a problem in itself.

    J
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