DragonFly commits List (threaded) for 2009-05
Re: DragonFly-220.127.116.114.gc5b83 master sys/platform/pc32/apic mpapic.c sys/platform/pc32/isa clock.c sys/platform/pc64/isa clock.c sys/platform/vkernel/platform systimer.c sys/sys systimer.h
: lapic timer: Finish the lapic timer support
Yah! It works! Awesome work!
lapic: divisor index 0, frequency 100489256 Hz
vmstat -i ... shows no more "clk" interrupt (as expected!)
(a) In your commit you said 'hw.lapci_timer_enable' instead of what
you really meant which was 'hw.lapic_timer_enable' :-)
(b) Here is a slight change to the interrupt vector code. The
FAST interrupt code also checks for a non-zero td->td_nest_count
before allowing the processing to occur, so I added that to the lapic
vector code too.
The use of td_nest_count is a bit of a hack to allow interrupt
thread preemption to work for slow interrupts. I bump td_nest_count
instead of entering a critical section when scheduling the ithread
(for slow interrupts) so the critical section tests in lwkt_schedule()
in the preemption checks work as expected.
(c) Lastly now that the APIC is in use we need some accounting for the
apic interrupt in 'systat -i' output. I added a line to increment
the V_INTR statistic. We might want to augment systat -vm 1 to
explicitly report clock interrupts somehow, maybe with a dummy
kernel-layer interrupt structure that we can name (e.g. "lapic"
vs the i8254's "clk"). I don't know the best solution.
The quick change in the patch below makes it show up in
sysctl vm.stats.sys.v_intr, but systat -vm 1 still doesn't
pick it up (maybe systat should just report vm.stats.sys.v_intr
for its 'total' instead of totalizing the interrupt stats itself).
(see same patch below)
I think you can enable the lapic timer by default in a few days, or even
now. I'm running it on my test boxes and will report any issues but it
appears to be solid as a rock.
diff --git a/sys/platform/pc32/apic/apic_vector.s b/sys/platform/pc32/apic/apic_vector.s
index a208f78..26b1d77 100644
@@ -411,9 +411,12 @@ Xtimer:
movl $0, lapic_eoi /* End Of Interrupt to APIC */
+ incl PCPU(cnt) + V_INTR
+ testl $-1,TD_NEST_COUNT(%ebx)
+ jne 1f
subl $8,%esp /* make same as interrupt frame */
pushl %esp /* pass frame by reference */