high system load when using i915kms

[Max Brazhnikov]

On Thu, 07 Mar 2013 16:47:23 +0200 Konstantin Belousov wrote:
> On Wed, Mar 06, 2013 at 10:56:52AM +0000, Max Brazhnikov wrote:
> > On Wed, 6 Mar 2013 08:15:37 +0200 Konstantin Belousov wrote:
> > > On Tue, Mar 05, 2013 at 12:24:51PM +0000, Max Brazhnikov wrote:
> > > > Hi,
> > > > 
> > > > I've switched recently to new xorg and kms driver. Sometimes after 
booting 
> > my
> > > > system (9.1-STABLE #0 r245741 amd64) shows high load:
> > > > 
> > > > interrupt                          total       rate
> > > > irq1: atkbd0                         612          0
> > > > irq9: acpi0                         3693          1
> > > > irq12: psm0                         7512          2
> > > > irq16: uhci0 uhci3             377172955     144069
> > > > irq20: hpet0                     2923357       1116
> > > > irq23: uhci1 ehci1                 47432         18
> > > > irq256: hdac0                      80799         30
> > > > irq257: alc0                       78474         29
> > > > irq258: iwn0                       19994          7
> > > > irq259: ahci0                     100016         38
> > > > irq260: vgapci0                    31250         11
> > > > Total                          380466094     145327
> > > > 
> > > > I've never seen this with old xorg. The problem is not always 
> > reproducible, 
> > > > but it's enough just to load i915kms module without staring X to 
trigger 
> > it.
> > > > 
> > > > Any idea?
> > > 
> > > So what is the complain ? Do you meaning that loading i915kms causes
> > > the spike in the interrupt rate on the irq16 line ?
> > 
> > I suspect it since the only change was update to newer xorg.
> Do you mean that the same kernel was kept,
> and only usermode components upgraded ?

Correct. The kernel and world were built from r245741 more  than month ago.
I used prebuilt Xorg packages from latest experimental ports, so the changes 
in the system are minimal.

 > This is plain impossible to cause the effect you described.
> > 
> > > What is the graphics part and the south bridge you are using ? Show
> > > the pciconf -lvc output.
> > 
> > http://people.freebsd.org/~makc/pciconf.output
> 
> I have exactly the same GM45 chipset in my laptop.
> 
> BTW, is the vmstat output you demonstrated in the first message, was for
> the system with running X ? I am asking about the presence of the rendering
> activity on the display, which would explain the significant count of
> the interrupts from GPU.

Yes, it was under KDE session, however the problem can be observe with plain X 
and xterm or even without them:
# cat test.sh 
#!/bin/sh
vmstat -i
kldload i915kms
sleep 10
vmstat -i
xinit &
sleep 10
vmstat -i

interrupt                          total       rate
irq1: atkbd0                         169          3
irq9: acpi0                           72          1
irq12: psm0                           24          0
irq16: uhci0 uhci3                    25          0
irq19: ehci0 uhci2                     2          0
irq20: hpet0                       20351        407
irq23: uhci1 ehci1                    95          1
irq256: hdac0                         71          1
irq257: alc0                         347          6
irq258: iwn0                        1624         32
irq259: ahci0                       4095         81
Total                              26875        537
interrupt                          total       rate
irq1: atkbd0                         169          2
irq9: acpi0                           72          1
irq12: psm0                           24          0
irq16: uhci0 uhci3               1533470      24733
irq19: ehci0 uhci2                     2          0
irq20: hpet0                       33165        534
irq23: uhci1 ehci1                    95          1
irq256: hdac0                         71          1
irq257: alc0                         509          8
irq258: iwn0                        2090         33
irq259: ahci0                       4273         68
irq260: vgapci0                        1          0
Total                            1573941      25386
interrupt                          total       rate
irq1: atkbd0                         187          2
irq9: acpi0                           94          1
irq12: psm0                           24          0
irq16: uhci0 uhci3               3056916      42457
irq19: ehci0 uhci2                     2          0
irq20: hpet0                       44423        616
irq23: uhci1 ehci1                    95          1
irq256: hdac0                         71          0
irq257: alc0                         634          8
irq258: iwn0                        2494         34
irq259: ahci0                       4772         66
irq260: vgapci0                       10          0
Total                            3109722      43190

  PID USERNAME     THR PRI NICE   SIZE    RES STATE   C   TIME   WCPU COMMAND
   11 root           2 155 ki31     0K    32K RUN     1   4:16 120.35% idle
   12 root          18 -84    -     0K   288K WAIT    0   0:57 76.34% intr

I've got this after second boot today, although I couldn't reproduce it 
yesterday even after ten attempts. But sometimes it's quite nasty and I have 
to reboot the system several times to get rid of it.

Max