High Interrupt rate since r279961 on STABLE/10 branch

[Ian Smith]

On Thu, 11 Jun 2015 09:43:15 +0800, Yanhui Shen wrote:
 > Hi,
 > 
 > Thanks, it works!
 > 
 > https://svnweb.freebsd.org/base/head/sys/dev/pci/vga_pci.c?r1=284012&r2=284011&pathrev=284012
 > 
 > 
 > 
 > 2015-06-11 0:38 GMT+08:00 Adrian Chadd <adrian at freebsd.org>:
 > 
 > > Hi,
 > >
 > > There was an update to freebsd-head a few days ago from hans - it
 > > disabled PCI interrupts for VGA until a driver claims it.
 > >
 > > See if that helps?

I'm glad it does, and can see the interrupt rate on vgapci0 was 173 when 
bad and 4 when good, but I'm completely at a loss to see how that might 
have affected the interrupt rate on uhci3, shown below as 189643 (!) 
when bad and, er, absent when good?

cheers, Ian

 > > > Device: ThinkPad R400 (Product ID: 278225C)
 > > > CPU: Intel Core 2 Duo processor T6570 (2.1 GHz)
 > > > GPU: Intel Integrated Graphics 4500MHD
 > > >
 > > > Output of "vmstat -i" with r284205 kernel (abnormal):
 > > > interrupt                    total              rate
 > > > irq1: atkbd0              1607             1
 > > > irq9: acpi0                 131958         104
 > > > irq12: psm0               4281            3
 > > > irq16: uhci3               239899376  189643
 > > > irq20: hpet0 uhci0     1426118      1127
 > > > irq21: uhci1               40315          31
 > > > irq23: ehci0               33                0
 > > > irq256: vgapci0          6059           4
 > > > irq257: em0               49220         38
 > > > irq258: hdac0            62                0
 > > > irq260: ahci0:ch0       17217          13
 > > > irq261: ahci0:ch1       23               0
 > > > Total                          241576269  190969
 > > >
 > > > Output of "vmstat -i" with r279958 kernel (normal):
 > > > interrupt                          total       rate
 > > > irq1: atkbd0                       48155          3
 > > > irq9: acpi0                      1581468        105
 > > > irq12: psm0                       209484         13
 > > > irq19: ehci1                       48099          3
 > > > irq20: hpet0 uhci0              17385585       1156
 > > > irq21: uhci1                      680884         45
 > > > irq23: ehci0                          31          0
 > > > irq256: vgapci0                  2611430        173
 > > > irq257: em0                      1342009         89
 > > > irq258: hdac0                     602220         40
 > > > irq260: ahci0:ch0                 236313         15
 > > > irq261: ahci0:ch1                     27          0
 > > > Total                           24745705       1646