Re: processes stuck in kqread

Eric Anderson wrote this message on Sun, Jul 22, 2007 at 16:27 -0500:
> 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

/me needs to read closer.

Thought it might be a yp issue:
 84667 top      0.005085 CALL  open(0x7fffffffdd00,O_RDONLY,<unused>0x1e)
 84667 top      0.005091 NAMI  "/var/yp/binding/centtech.com.2"
 84667 top      0.005105 RET   open -1 errno 2 No such file or directory
[...]
 84667 top      0.005461 CALL  socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP)
 84667 top      0.005468 RET   socket 5
[...]
 84667 top      0.005533 CALL  bind(0x5,0x7fffffffda10,0x10)
 84667 top      0.005542 RET   bind 0
[...]
 84667 top      0.006028 CALL  sendto(0x5,0x800c11ac4,0x38,0,0x800c11808,0x10)

>  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
>        ""

Looks like it's trying to contact the yp server and isn't getting a
response...  Check your user/host name lookup...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."