processes stuck in kqread

[Eric Anderson]

John-Mark Gurney wrote:
> kevin kramer wrote this message on Wed, Jul 18, 2007 at 11:10 -0500:
>> I have been having issues for some time on -CURRENT. My latest update 
>> was 7/11. I have identified these processes as being stuck in kqread 
>> while waiting for them to continue.
>>
>> Processes that I know are a problem:
>> sshd - I can watch a login and the process goes from Select to kqread, 
>> takes about 3-4 minutes to get a login prompt
>> top - takes about 2-3 minutes to come up
>> tar - never really even starts to read data in and stays in kqread
>>
>> Processes not affected:
>> scp
>> gstat
>> cvsup
>> make
>>
>> This machine is running AMD64 GENERIC kernel on a Dual-Core Xeons.
>> dmesg.txt and top-trace.txt here, http://users.centtech.com/~kramer/snapshot
>>
>> What do I do to debug this?
> 
> running the process under ktrace would help identify what it is waiting
> for...  Though if it usually hangs for a minute or two in kqread, and
> then continues, it's probably a DNS lookup issue...
> 


You mean like the one he put here:

http://users.centtech.com/~kramer/snapshot/top-trace.txt


:)

A quick snippet:

  84667 top      0.006110 RET   sendto 56/0x38
  84667 top      0.006128 CALL 
kevent(0x6,0x800c11910,0x1,0x7fffffffdad0,0x1,0x7fffffffdb10)
  84667 top      5.008057 GIO   fd 6 wrote 32 bytes
        0x0000 0500 0000 0000 0000 ffff 0100 0000 0000 0000 0000 0000 
0000 0000 0000 0000 0000 
|................................|

  84667 top      5.008073 GIO   fd 6 read 0 bytes
        ""
  84667 top      5.008078 RET   kevent 0
  84667 top      5.008086 CALL  gettimeofday(0x7fffffffdb20,0)
  84667 top      5.008091 RET   gettimeofday 0
  84667 top      5.008096 CALL 
sendto(0x5,0x800c11ac4,0x38,0,0x800c11808,0x10)
  84667 top      5.008139 GIO   fd 5 wrote 56 bytes
        0x0000 4696 2a64 0000 0000 0000 0002 0001 86a0 0000 0002 0000 
0003 0000 0000 0000 0000 0000 0000 0000 0000 
|F.*d....................................|
        0x0028 0001 86a7 0000 0002 0000 0006 0000 0000 
                                             |................|

  84667 top      5.008155 RET   sendto 56/0x38
  84667 top      5.008163 CALL 
kevent(0x6,0x800c11910,0,0x7fffffffdad0,0x1,0x7fffffffdb10)
  84667 top      15.007883 GIO   fd 6 wrote 0 bytes
        ""


Eric