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Date:      Fri, 8 Mar 2013 11:38:13 -0800
From:      Kevin Oberman <rkoberman@gmail.com>
To:        Max Brazhnikov <makc@freebsd.org>
Cc:        freebsd-x11@freebsd.org, freebsd-usb@freebsd.org
Subject:   Re: high system load when using i915kms
Message-ID:  <CAN6yY1u%2BSi3YebRpkimTNda0CvWdZoYM5LrVT_VwySQaE1w0OA@mail.gmail.com>
In-Reply-To: <1382092.A6MSmtKV3F@mercury.ph.man.ac.uk>
References:  <2460779.xZBtdeG4eu@mercury.ph.man.ac.uk> <2268582.B3fxbEy5KG@mercury.ph.man.ac.uk> <20130307144723.GZ3794@kib.kiev.ua> <1382092.A6MSmtKV3F@mercury.ph.man.ac.uk>

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On Fri, Mar 8, 2013 at 10:03 AM, Max Brazhnikov <makc@freebsd.org> wrote:

> 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
>

So the issue is that that the interrupts from one or another of the USB
devices has exploded from near zero to around 40K when the kernel module is
loaded?

A couple of possibly irrelevant questions. Do you normally manually load
the module? I did not research the issue, but when I manually load the
module I was seeing things just grind to a halt. If I started Gnome, the
module was loaded automatically by X, and things worked.

Why loading the Intel KMS module would cause a massive increase in
interrupts on a USB interface completely baffles me, but I suspect some
sort of race is going on when the module is pre-loaded.
-- 
R. Kevin Oberman, Network Engineer
E-mail: rkoberman@gmail.com



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