| Subject | Re: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U8 | From | Lee Revell <> | Date | Wed, 20 Oct 2004 11:37:36 -0400 |
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On Wed, 2004-10-20 at 10:18, Ingo Molnar wrote: > note that the keyboard and USB interrupts are SCHED_OTHER by default, so > they could be delayed quite long depending on the workload.
Why is this the default behavior? It seems like you would want all IRQ threads to be SCHED_FIFO by default. Otherwise it seems like the scheduler could decide to run a normal userspace process (like, say, X) while an IRQ thread is runnable.
Is it really a good idea for IRQ threads to be subject to the whims of the scheduler?
Also, on modern machines, this would effectively make all IRQ threads SCHED_OTHER because the USB port shares an interrupt with everything:
0: 36676353 XT-PIC timer 0/76353 1: 8759 XT-PIC i8042 5/8759 2: 0 XT-PIC cascade 0/0 8: 4 XT-PIC rtc 0/4 10: 0 XT-PIC uhci_hcd 0/0 11: 210713 XT-PIC uhci_hcd, eth0 0/10713 12: 0 XT-PIC uhci_hcd 0/0 15: 79277 XT-PIC ide1 0/79276 NMI: 0 ERR: 0
Lee
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