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    SubjectRe: Ctrl+C doesn't interrupt process waiting for I/O
    Jeremy Fitzhardinge wrote:
    > 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's filesystem dependent; if you mount an nfs filesystem with the
    'intr' mount option, it will be interruptible (which makes sense, as it
    is impossible to guarantee the server's responsiveness).

    --
    I have a truly marvellous patch that fixes the bug which this
    signature is too narrow to contain.

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