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

[Taras Savchuk]

LI Xin пишет:
> Taras Savchuk wrote:
>   
>> LI Xin пишет:
>>     
>>> Paul Lathrop wrote:
>>>  
>>>       
>>>> Taras Savchuk wrote:
>>>>    
>>>>         
>>>>> Hi to ALL!
>>>>>
>>>>> I have dovecot-1.0r7 installed on FreeBSD 6.1, using kqueue and
>>>>> Maildir (<20 mailboxes, < 0,5 Gb size). Periodically CPU load of imap
>>>>> processes increasing up to 60-80%.
>>>>> Is it normall behavior or not? May be somebody had such kind of
>>>>> problems?
>>>>>
>>>>>       
>>>>>           
>>>> I have also experienced this behavior, which is quite bothersome because
>>>> I sold my supervisor on Dovecot by talking about performance and low
>>>> resource requirements...
>>>>     
>>>>         
>>> 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,
>>>   
>>>       
>> I cought imap while eating much CPU (~80%) and run ktrace -t + -p <bad
>> process pid>.
>> It's kdump -E output, many gettimeofday() calls, is it normal? :
>>
>> mail2# kdump -E -f ktrace.out | less
>> 26208 imap     0.000000 RET   kevent 0
>> 26208 imap     0.000042 CALL  gettimeofday(0x80c2c60,0x80c2c68)
>> 26208 imap     0.000046 RET   gettimeofday 0
>> 26208 imap     0.000061 CALL  gettimeofday(0xbfbfe9a0,0)
>> 26208 imap     0.000064 RET   gettimeofday 0
>> 26208 imap     0.000078 CALL  kevent(0x4,0,0,0x80d1000,0x5,0xbfbfe998)
>> 26208 imap     0.000082 RET   kevent 0
>> 26208 imap     0.000100 CALL  gettimeofday(0x80c2c60,0x80c2c68)
>> 26208 imap     0.000103 RET   gettimeofday 0
>> 26208 imap     0.000116 CALL  gettimeofday(0xbfbfe9a0,0)
>> 26208 imap     0.000119 RET   gettimeofday 0
>> 26208 imap     0.000131 CALL  kevent(0x4,0,0,0x80d1000,0x5,0xbfbfe998)
>> 26208 imap     0.474998 RET   kevent 0
>>     
> [snip]
>
> This looks quite normal...  I am not really sure about what is
> happening.  Is the CPU consumed by in-kernel operation?  (systat -vm  or
> top's output would be helpful)
>
> Cheers,
>   
0,5 second for kevent call is normal?

 > 26208 imap     0.000131 CALL  kevent(0x4,0,0,0x80d1000,0x5,0xbfbfe998)
 > 26208 imap     0.474998 RET   kevent 0

-- 
С уважением, Савчук Тарас
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