Hello Steven,
Steven Rostedt wrote:
John Sigler wrote:
I need to change the priorities of several soft and hard IRQ handlers.
Namely,
o reduce the prio of "softirq-timer" handler to 10
o reduce the prio of IRQ14 and IRQ15 handlers to 20
(my flash drives do not support DMA BTW...)
o boost the prio of my I/O boards' IRQ handlers to 60
(there can be 1 or 2 boards, the driver is a kernel module
which is loaded after the system has booted.)
I've written a short program that calls
sched_setscheduler(pid, SCHED_FIFO, ¶m);
with the appropriate pid, which I look up using ps -ef
Look for the program "chrt". It does this for you. This program is
available in all major distributions of Linux.
Thanks for the tip.
For the record, I found schedutils on Robert Love's page:
http://rlove.org/
http://rlove.org/misc/schedutils-1.5.0.tar.gz
However, I had already solved that part of the problem with a
program of my own.
My real problem is: the IRQ handlers for the I/O boards are
only instantiated when the kernel module is inserted. How do
I /reliably/ determine their pid?
e.g. on one system, the IRQ handler for my I/O board is IRQ5
with pid 745. On another system, it's IRQ20 with pid 808.
On a third system they're IRQ20 and IRQ21 with pid 239 and 240.
The only solution I see is to examine /proc/interrupts to find the
IRQ handler(s) then ps to lookup their pid, but that feels like a
dirty hack.
These interrupt handlers are all spawned by kthreadd. I thought
there would be some way to ask kthreadd to tweak the priorities.
I need to automate the process of tweaking priorities.
Can someone offer advice and / or pointers?
Perhaps look at one of the startup scripts, and add the chrt
command there.
Which startup scripts?
Regards.
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