Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q7

Ingo Molnar
2004-09-02T05:35:43Z

* K.R. Foley <kr@cybsft.com> wrote:

> This is an interesting one. ~3.9ms generated here by amlat in do_IRQ:

the overhead is not in do_IRQ():

> 00000001 0.000ms (+0.000ms): n_tty_receive_buf (pty_write)
> 00010001 3.992ms (+3.992ms): do_IRQ (n_tty_receive_buf)

the overhead is always relative to the previous entry - so the overhead
was in n_tty_receive_buf() [that is the function that was interrupted by
do_IRQ()]. But it's a bit weird - you should have gotten timer IRQs
every 1 msec. Does n_tty_receive_buf() run with irqs disabled perhaps?

Ingo