Taras Savchuk wrote:
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
It seems that the call is from lib/ioloop-kqueue.c's io_loop_handler_run(), but I did not really follow the logic there. Personally I think io_loop_get_wait_time() can be improved in some (tricky?) way so we get better performance on FreeBSD without getting the penalty of its expensive gettimeofday() call.
Cheers,
Xin LI delphij@delphij.net http://www.delphij.net/ FreeBSD - The Power to Serve!