[Comm] CPU iowait слишком велико

[Vladimir Karpinsky]

14.07.2012 0:47, Arcady V. Ivanov пишет:
> Посмотрите с помощью iotop.
> Думаю, это проблема RAID-а.

Поставил iotop, но пока там ничего а глаза не бросилось, впрочем м.б. я не 
знаю на что смотреть.

Cron иногда (~1 раза в месяц) присылает сообщения вида:

checkarray: I: selecting idle I/O scheduling class for resync of md0.
checkarray: I: selecting idle I/O scheduling class for resync of md1.
checkarray: I: selecting idle I/O scheduling class for resync of md2.
checkarray: I: selecting idle I/O scheduling class for resync of md3.

> У меня такая же фигня была.
> Если dmesg рисует deadlock-и на 120 сек, это проблема hiresolution таймера.

# dmesg | grepp md
[9735123.335851] md: using 128k window, over a total of 20478912k.
[9735401.818806] md: md2: data-check done.
[12129217.385503] md: data-check of RAID array md0
[12129217.385506] md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
[12129217.385508] md: using maximum available idle IO bandwidth (but not 
more than 200000 KB/sec) for data-check.
[12129217.385510] md: using 128k window, over a total of 8707008k.
[12129217.620759] md: delaying data-check of md1 until md0 has finished 
(they share one or more physical units)
[12129217.631725] md: delaying data-check of md2 until md1 has finished 
(they share one or more physical units)
[12129217.631803] md: delaying data-check of md1 until md0 has finished 
(they share one or more physical units)
[12129217.642750] md: delaying data-check of md3 until md1 has finished 
(they share one or more physical units)
[12129217.642753] md: delaying data-check of md1 until md0 has finished 
(they share one or more physical units)
[12129217.642757] md: delaying data-check of md2 until md1 has finished 
(they share one or more physical units)
[12129328.050106] md: md0: data-check done.
[12129328.066514] md: delaying data-check of md2 until md1 has finished 
(they share one or more physical units)
[12129328.066519] md: data-check of RAID array md1
[12129328.066521] md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
[12129328.066522] md: using maximum available idle IO bandwidth (but not 
more than 200000 KB/sec) for data-check.
[12129328.066525] md: using 128k window, over a total of 2095040k.
[12129328.066955] md: delaying data-check of md3 until md1 has finished 
(they share one or more physical units)
[12129352.859826] md: md1: data-check done.
[12129352.874434] md: data-check of RAID array md3
[12129352.874437] md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
[12129352.874439] md: using maximum available idle IO bandwidth (but not 
more than 200000 KB/sec) for data-check.
[12129352.874442] md: using 128k window, over a total of 945476480k.
[12129352.874452] md: delaying data-check of md2 until md3 has finished 
(they share one or more physical units)
[12154551.743772] md: md3: data-check done.
[12154551.775858] md: data-check of RAID array md2
[12154551.775861] md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
[12154551.775862] md: using maximum available idle IO bandwidth (but not 
more than 200000 KB/sec) for data-check.
[12154551.775865] md: using 128k window, over a total of 20478912k.
[12154932.231802] md: md2: data-check done.
[13264118.543397] mdadm: sending ioctl 1261 to a partition!
[13264118.543399] mdadm: sending ioctl 1261 to a partition!
[13264118.725254] mdadm: sending ioctl 1261 to a partition!
[13264118.725256] mdadm: sending ioctl 1261 to a partition!
[13264118.807387] mdadm: sending ioctl 1261 to a partition!
[13264118.807389] mdadm: sending ioctl 1261 to a partition!
[13264118.918880] mdadm: sending ioctl 1261 to a partition!
[13264118.918883] mdadm: sending ioctl 1261 to a partition!
[13264119.015867] mdadm: sending ioctl 1261 to a partition!
[13264119.015870] mdadm: sending ioctl 1261 to a partition!
[13264125.165873] mdadm: sending ioctl 1261 to a partition!
[13264125.165875] mdadm: sending ioctl 1261 to a partition!
[13264125.283665] mdadm: sending ioctl 1261 to a partition!
[13264125.283668] mdadm: sending ioctl 1261 to a partition!
[13264125.354219] mdadm: sending ioctl 1261 to a partition!
[13264125.354221] mdadm: sending ioctl 1261 to a partition!
[13264125.459097] mdadm: sending ioctl 1261 to a partition!
[13264125.459099] mdadm: sending ioctl 1261 to a partition!
[13264125.530656] mdadm: sending ioctl 1261 to a partition!
[13264125.530658] mdadm: sending ioctl 1261 to a partition!

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		Владимир.