high load system do not take all CPU time

[Коньков Евгений]

Здравствуйте, Daniel.

Вы писали 18 декабря 2011 г., 17:52:00:

DS> --As of December 17, 2011 10:29:42 AM +0200, Коньков Евгений 
DS> is alleged to have said:

>> How to debug why system do not use free CPU resouces?
>>
>> On this pictures you can see that CPU can not exceed 400tics
>> http://piccy.info/view3/2368839/c9022754d5fcd64aff04482dd360b5b2/
>> http://piccy.info/view3/2368837/a12aeed98681ed10f1a22f5b5edc5abc/
>> http://piccy.info/view3/2368836/da6a67703af80eb0ab8088ab8421385c/
>>
>>
>> On these pictures you can see that problems begin with trafic on re0
>> when CPU load rise to "maximum"
>> http://piccy.info/view3/2368834/512139edc56eea736881affcda490eca/
>> http://piccy.info/view3/2368827/d27aead22eff69fd1ec2b6aa15e2cea3/
>>
>> But there is 25% CPU idle yet at that moment.

DS> <snip>

>># top -SIHP
>> last pid: 93050;  load averages:  1.45,  1.41,  1.29
>> up 9+16:32:06  10:28:43 237 processes: 5 running, 210 sleeping, 2
>> stopped, 20 waiting
>> CPU 0:  0.8% user,  0.0% nice,  8.7% system, 17.7% interrupt, 72.8% idle
>> CPU 1:  0.0% user,  0.0% nice,  9.1% system, 20.1% interrupt, 70.9% idle
>> CPU 2:  0.4% user,  0.0% nice,  9.4% system, 19.7% interrupt, 70.5% idle
>> CPU 3:  1.2% user,  0.0% nice,  6.3% system, 22.4% interrupt, 70.1% idle
>> Mem: 843M Active, 2476M Inact, 347M Wired, 150M Cache, 112M Buf, 80M Free
>> Swap: 4096M Total, 15M Used, 4080M Free

DS> --As for the rest, it is mine.

DS> You are I/O bound; most of your time is spent in interrupts.  The CPU is
DS> dealing with things as fast as it can get them, but it has to wait for the
DS> disk and/or network card to get them to it.  The CPU is not your problem;
DS> if you need more performance, you need to tune the I/O.  (And possibly get
DS> better I/O cards, if available.)

DS> Daniel T. Staal

can I get interrupt limit or calculate it before that limit is
reached?

interrupt source is internal card:
# vmstat -i
interrupt                          total       rate
irq14: ata0                       349756         78
irq16: ehci0                        7427          1
irq23: ehci1                       12150          2
cpu0:timer                      18268704       4122
irq256: re0                     85001260      19178
cpu1:timer                      18262192       4120
cpu2:timer                      18217064       4110
cpu3:timer                      18210509       4108
Total                          158329062      35724

Have you any good I/O tuning links to read?

-- 
С уважением,
 Коньков                          mailto:kes-kes at yandex.ru