[lkml]   [2002]   [Aug]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: device driver / char module interrupt vector -> user space code
    On Fri, Aug 09, 2002 at 11:34:00AM +0100, Alan Cox wrote:
    > On Fri, 2002-08-09 at 09:49, SA wrote:
    > > I am writing a char module for a PCI stage controller and want to add the
    > > following functionality;
    > >
    > > The device will generate an interrupt (or software trigger) and I want this to
    > > run a bit of user code with relatively latency. (<1ms). I am unclear how to
    > > do this while still separating the user from the kernel code and maintaining
    > > security - would this usually be handled by issuing a signal to the user space
    > > process? if so how and what latency can I expect?
    > You could deliver a signal, or if appropriate you can have a system call
    > that blocks until the IRQ. To get good reliable latency, mlockall() the
    > process you need to be real time, and set it to a real time scheduling
    > priority.

    If you noticed the discussion about signal delivery and context switch
    latency, a syscall (can be ioctl on special device) waiting for the
    event would be faster than signal.

    Jan 'Bulb' Hudec <>
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:27    [W:0.044 / U:1.192 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site