usb/176913: High interrupt load with ehci

[Christian Jurk]

>Number:         176913
>Category:       usb
>Synopsis:       High interrupt load with ehci
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-usb
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Mar 13 10:30:01 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Christian Jurk
>Release:        9.1
>Organization:
>Environment:
FreeBSD nodame 9.1-RELEASE FreeBSD 9.1-RELEASE #0 r243825: Tue Dec  4 09:23:10 UTC 2012     root at farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64
>Description:
The machine is having constantly high interrupt load.

# vmstat -i
cjurk at nodame:~% vmstat -i
interrupt                          total       rate
irq16: ehci0                  6264477215      85601
irq18: xhci0                    32405333        442
irq23: ehci1                     4689051         64
cpu0:timer                      29846776        407
irq264: hdac0                         62          0
irq265: re0                     93526302       1277
irq267: ahci0                     737621         10
cpu1:timer                      55424818        757
Total                         6481107178      88561

# dmesg | grep ehci
ehci0: <EHCI (generic) USB 2.0 controller> mem 0xf7e08000-0xf7e083ff irq 16 at device 26.0 on pci0
usbus0 on ehci0
ehci1: <EHCI (generic) USB 2.0 controller> mem 0xf7e07000-0xf7e073ff irq 23 at device 29.0 on pci0
usbus2 on ehci1

# top -S
last pid: 75321;  load averages:  0.17,  0.25,  0.24    up 0+20:22:38  11:20:28
70 processes:  2 running, 67 sleeping, 1 waiting
CPU:  0.0% user,  0.0% nice,  0.0% system, 27.4% interrupt, 72.6% idle
Mem: 46M Active, 792M Inact, 2863M Wired, 34M Cache, 408M Buf, 113M Free
Swap: 4096M Total, 7364K Used, 4089M Free

  PID USERNAME    THR PRI NICE   SIZE    RES STATE   C   TIME   WCPU COMMAND
   11 root          2 155 ki31     0K    32K RUN     1  31.2H 150.29% idle
   12 root         16 -84    -     0K   256K WAIT    0 200:06 50.49% intr
    0 root        156  -8    0     0K  2496K -       1 149:25  0.00% kernel
   15 root         13 -68    -     0K   208K -       0   7:22  0.00% usb
21961 root          4  -8    -     0K    80K tx->tx  0   2:27  0.00% zfskern
80209 cjurk         1  20    0 16560K  1328K select  0   1:22  0.00% top
    9 root          1  16    -     0K    16K syncer  1   1:12  0.00% syncer
   13 root          3  -8    -     0K    48K -       0   0:55  0.00% geom
   14 root          1 -16    -     0K    16K -       1   0:42  0.00% yarrow
22333 root          1  20    0 40724K  1044K nanslp  0   0:16  0.00% nmbd
 1157 root          1  20    0 12052K   532K select  0   0:16  0.00% powerd
29397 cjurk         1  20    0 22928K  1600K select  0   0:11  0.00% screen
 1154 root          1  20    0 22196K  1268K select  1   0:08  0.00% ntpd
   19 root          1 -16    -     0K    16K sdflus  1   0:06  0.00% softdepflu
    5 root          1 -16    -     0K    16K psleep  1   0:05  0.00% pagedaemon
   16 root          1 -16    -     0K    16K tzpoll  1   0:04  0.00% acpi_therm
 1181 root          1  20    0 20252K  2148K select  1   0:03  0.00% sendmail

The only device connected to USB is a external hard disk, which is used as storage disk (ZFS).
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: