Re: DragonFly-2.3.0.864.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

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

:    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!)

    Three notes.

    (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.

	(see below)

    (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.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>

diff --git a/sys/platform/pc32/apic/apic_vector.s b/sys/platform/pc32/apic/apic_vector.s
index a208f78..26b1d77 100644
--- a/sys/platform/pc32/apic/apic_vector.s
+++ b/sys/platform/pc32/apic/apic_vector.s
@@ -411,9 +411,12 @@ Xtimer:
 	movl	$0, lapic_eoi		/* End Of Interrupt to APIC */
 	FAKE_MCOUNT(15*4(%esp))
 
+	incl    PCPU(cnt) + V_INTR
 	movl	PCPU(curthread),%ebx
 	cmpl	$TDPRI_CRIT,TD_PRI(%ebx)
 	jge	1f
+	testl	$-1,TD_NEST_COUNT(%ebx)
+	jne	1f
 	subl	$8,%esp			/* make same as interrupt frame */
 	pushl	%esp			/* pass frame by reference */
 	incl	PCPU(intr_nesting_level)