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SubjectRe: [patch] Re: setitimer lowlatency-2.2.13-A1 questions

On Tue, 7 Dec 1999, Andrea Arcangeli wrote:
> >This allows me to see the irqdis_nobh in my ktrace, however, I never
> >do see it. [..]
>
> That's fine because you must not see it. If you see it it means it should
> BUG() or you won't be able to achieve the best latency.
>
What is BUG()?

>
> Could you provide also a plain `ktrace -m System.map -s ???`? The hex
> addresses (not only the resolved symbols) and CPU information are very
> interesting.
>
Sorry, not anymore. I have new test results and I will provide a plain
(mostly) ktrace dump. I did not enable CPU info since I am not SMP.
Why are the hex addresses interesting?
Will enabling CPU info be useful in my case?

New test case follows:
c010a64d do_IRQ +<d/54> ( 0.39 ) ( 123767.76 ) pid(5392)
c010a1cf do_8259A_IRQ +<13/b4> ( 2.74 ) ( 123768.15 ) pid(5392)
c010a4f4 handle_IRQ_event +<10/78> ( 0.62 ) ( 123770.89 ) pid(5392)
c010e1ce timer_interrupt +<12/12c> ( 6.21 ) ( 123771.51) pid(5392)
c011418d do_timer +<d/5c> ( 1.20 ) ( 123777.72 ) pid(5392)
c010a109 enable_8259A_irq +<d/3c> ( 0.83 ) ( 123778.92 ) pid(5392)
c010a672 do_IRQ +<32/54> ( 0.13 ) ( 123779.75 ) pid(5392)
c011b630 do_bottom_half +<10/78> ( 0.14 ) ( 123779.88 ) pid(5392)
c010a68d do_IRQ +<4d/54> ( 1.19 ) ( 123780.02 ) pid(5392)
c0176841 tcp_send_delayed_ack +<d/60> ( 0.46 ) ( 123781.21 ) pid(5392)
c0112e7a add_timer +<e/190> ( 1.16 ) ( 123781.67 ) pid(5392)
c010a68d do_IRQ +<4d/54> ( 8294.68 ) ( 123782.83 ) pid(5392)
^^^----Ouch! Notice timer_bh is never run
until *after* the next timer_interrupt
c010a64d do_IRQ +<d/54> ( 0.44 ) ( 132077.51 ) pid(5392)
c010a1cf do_8259A_IRQ +<13/b4> ( 2.21 ) ( 132077.95 ) pid(5392)
c010a4f4 handle_IRQ_event +<10/78> ( 0.43 ) ( 132080.16 ) pid(5392)
c010e1ce timer_interrupt +<12/12c> ( 5.69 ) ( 132080.59 ) pid(5392)
c011418d do_timer +<d/5c> ( 0.77 ) ( 132086.28 ) pid(5392)
c010a109 enable_8259A_irq +<d/3c> ( 0.81 ) ( 132087.06 ) pid(5392)
c010a672 do_IRQ +<32/54> ( 0.13 ) ( 132087.86 ) pid(5392)
c011b630 do_bottom_half +<10/78> ( 0.66 ) ( 132087.99 ) pid(5392)
c0113e54 timer_bh +<10/33c> ( 0.77 ) ( 132088.65 ) pid(5392)

What is going on here?

Wm


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