[Dovecot] FreeBSD 6.1-RELEASE/kqueue high CPU load

[Taras Savchuk]

LI Xin пишет:
> Taras Savchuk wrote:
> [snip]
>   
>>> What if you get some output from ktrace/kdump?  Additionally, try to
>>> force the process to save a coredump and investigate its .core with gdb
>>> would help tracking down the issue...
>>>
>>> Note that because when using kqueue the process should get a "kqread" if
>>> it is waiting for kqueue event.  If the process is stuck in "RUN" state
>>> then a coredump would be more helpful.
>>>
>>> Cheers,
>>>   
>>>       
>> ~20000 calls to gettimeofday() per second. Is it normall?
>>     
>
> No!  What's more, gettimeofday() is much more expensive on FreeBSD than
> its Linux counterpart, as it provides higher resolution time which is
> not useful for many applications.
>
> My guess is that your imap instance is stuck in a state where either
> kevent() is called with a zero ts structure (which is effectively a
> poll) every time, or some other weird thing happend.
>
>   
>> mail2# cat k.dov.l.txt | grep CALL | grep gettimeofday | wc -l
>> 1195552
>> mail2# head -n 1 k.dov.l.txt
>> 20910 imap 0.000000 CALL gettimeofday(0x80c2c60,0x80c2c68)
>> mail2# tail -n 1 k.dov.l.txt
>> 20910 imap 51.826065 RET gettimeofday 0
>>     
>
> Are these gettimeofday() calls called one by one?  Or is there any other
> calls between gettimeofday's?
>
> Cheers,
>   
It's a statistics for the same ktrace file (52 seconds):

mail2# cat k.dov.l.txt | wc -l
 3991592
mail2# cat k.dov.l.txt | grep kevent | grep CALL | wc -l
  797033
mail2# cat k.dov.l.txt | grep kevent | grep RET | wc -l
  797033
mail2# cat k.dov.l.txt | grep gettimeofday  | grep CALL | wc -l
 1195552
mail2# cat k.dov.l.txt | grep gettimeofday | grep RET | wc -l
 1195556
mail2#

and it's tipical chunk:

 20910 imap     51.825657 RET   kevent 1
 20910 imap     51.825712 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.825715 RET   gettimeofday 0
 20910 imap     51.825734 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.825737 RET   gettimeofday 0
 20910 imap     51.825755 CALL  kevent(0x5,0,0,0xbfbfe940,0x1,0xbfbfe938)
 20910 imap     51.825759 RET   kevent 1
 20910 imap     51.825778 CALL  gettimeofday(0xbfbfe9a0,0)
 20910 imap     51.825782 RET   gettimeofday 0
 20910 imap     51.825801 CALL  kevent(0x4,0,0,0x80d1000,0x5,0xbfbfe998)
 20910 imap     51.825804 RET   kevent 1
 20910 imap     51.825823 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.825826 RET   gettimeofday 0
 20910 imap     51.825844 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.825847 RET   gettimeofday 0
 20910 imap     51.825864 CALL  kevent(0x5,0,0,0xbfbfe940,0x1,0xbfbfe938)
 20910 imap     51.825869 RET   kevent 1
 20910 imap     51.825888 CALL  gettimeofday(0xbfbfe9a0,0)
 20910 imap     51.825892 RET   gettimeofday 0
 20910 imap     51.825910 CALL  kevent(0x4,0,0,0x80d1000,0x5,0xbfbfe998)
 20910 imap     51.825914 RET   kevent 1
 20910 imap     51.825932 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.825936 RET   gettimeofday 0
 20910 imap     51.825953 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.825957 RET   gettimeofday 0
 20910 imap     51.825974 CALL  kevent(0x5,0,0,0xbfbfe940,0x1,0xbfbfe938)
 20910 imap     51.825978 RET   kevent 1
 20910 imap     51.825997 CALL  gettimeofday(0xbfbfe9a0,0)
 20910 imap     51.826000 RET   gettimeofday 0
 20910 imap     51.826019 CALL  kevent(0x4,0,0,0x80d1000,0x5,0xbfbfe998)
 20910 imap     51.826022 RET   kevent 1
 20910 imap     51.826041 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.826044 RET   gettimeofday 0
 20910 imap     51.826062 CALL  gettimeofday(0x80c2c60,0x80c2c68)
 20910 imap     51.826065 RET   gettimeofday 0

-- 
С уважением, Савчук Тарас
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