Hello!
I develop a network interface driver and I've the following issue...
I create a kernel thread which has the following thread handler:
static int com_thread( void *data )
{
daemonize( "comthread" );
allow_signal( SIGTERM );
while( !signal_pending(current) ) {
if(receive(...)) {
process_received_data(...);
}
}
complete_and_exit(&threadcomplete, 0);
}
As you can see, the thread is polling a network card (i.e. Message Queue
of a SCI network card).
I know that polling normally is no good idea but the system, where this
driver shall run on, has 8 cores and we want to reserve exactly one core
for the polling work to get low latencies...
But now there are two problems:
1. problem is that the kernel thread doesn't get any signals which are
sent to it. A possibility is to use a variable instead of
"!signal_pending(current)" to advise the thread to exit. But I would
like to know why the thread gets no signals until I insert a sleep
function, like "msleep(1)", into the while loop.
2. problem is the stability of the system. Although there are 7 other
"free" CPUs which could do the rest of the kernel's work, the system
becomes very unstable - sometimes it freezes. Why does this happen? I've
set the nice level of the thread to 19 but this didn't help...
I know... the method is very naive. So, does anyone of you know a better
way to reserve a CPU for polling?
Many Thanks for your help!!!
Best regards,
Lukas
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