Long IO pauses

From: Jan Dittmer
Date: Sun Oct 22 2006 - 15:31:47 EST


Doing 10*bonnie++ and a cp of a 1 gb taking ages (2+h), this interesting
vmstat strace can be produced. Notice the ~28s of almost no i/o
activity.

Setup is ext3 on dm-crypt on loop on RAID5. Kernel 2.6.18, amd64,
cfq io scheduler. Changing the scheduler to deadline leads to the
same result. Seems to be seek bound would be my guess. But
virtually _no_ io for 30s??

Ideas?

Thanks,

Jan


procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
27 2 0 15948 7184 1671096 0 0 42 531 71 99 49 1 47 3
24 2 0 15496 7168 1669868 0 0 28 85196 2596 3840 33 67 0 0
26 2 0 14696 7212 1673868 0 0 104 71388 2384 7371 32 68 0 0
26 1 0 16368 7216 1662732 0 0 412 79600 2258 6644 37 63 0 0
26 0 0 16320 7232 1668900 0 0 40 97080 2212 9306 33 67 0 0
25 0 0 15324 7212 1668804 0 0 4 109204 2290 8091 34 66 0 0
27 0 0 16648 7232 1670416 0 0 0 100952 2329 10752 34 66 0 0
23 2 0 15628 7292 1675568 0 0 92 88624 1595 1853 30 64 0 7
26 1 0 16232 7356 1674360 0 0 0 101036 1926 5837 36 64 0 0
28 1 0 16368 7432 1671596 0 0 4 99812 1601 12745 32 69 0 0
27 2 0 15296 7460 1674416 0 0 20 101932 1641 4563 35 65 0 0
1 22 0 17924 7440 1677156 0 0 416 67320 990 4569 31 54 0 15
0 23 0 20668 7480 1677964 0 0 100 69324 2630 39412 0 23 4 73
0 23 0 24756 7480 1677992 0 0 8 3368 1609 15392 0 6 0 94
0 22 0 27740 7492 1678032 0 0 20 3840 1524 15311 0 4 1 95
0 23 0 28368 7508 1678048 0 0 16 10460 1545 16908 0 8 1 91
0 22 0 29368 7508 1678060 0 0 44 51828 2445 35456 0 18 4 77
0 22 0 30244 7508 1678112 0 0 0 53984 2020 32759 0 19 2 79
0 22 0 38400 7524 1678104 0 0 0 22644 3493 20678 0 14 3 83
0 22 0 39284 7524 1678104 0 0 0 16 474 403 0 0 0 100
0 22 0 40400 7524 1678112 0 0 0 0 458 310 0 0 0 100
11 22 0 41532 7532 1678112 0 0 0 32 567 532 0 1 0 99
0 22 0 42540 7532 1678112 0 0 0 24 472 497 0 0 0 100
0 22 0 43544 7532 1678112 0 0 0 8 467 374 0 0 0 100
1 22 0 44668 7540 1678104 0 0 12 0 502 367 0 0 0 100
0 22 0 47716 7540 1678112 0 0 0 0 466 322 0 0 0 100
0 22 0 51932 7540 1678120 0 0 0 0 548 336 0 0 0 100
0 22 0 55360 7540 1678120 0 0 0 0 464 320 0 0 0 100
0 22 0 55492 7540 1678120 0 0 0 0 463 307 0 0 15 85
4 22 0 55492 7568 1678108 0 0 12 100 504 705 0 1 24 76
1 22 0 55616 7568 1678120 0 0 0 0 481 333 0 0 15 84
0 22 0 55748 7568 1678120 0 0 0 0 585 373 0 0 50 50
0 22 0 55872 7568 1678120 0 0 0 12 467 359 0 0 50 50
0 22 0 55872 7568 1678120 0 0 0 8 463 341 0 0 50 50
0 22 0 55996 7568 1678120 0 0 0 0 457 290 0 0 50 50
0 22 0 55996 7588 1678112 0 0 4 76 490 499 0 0 50 50
0 22 0 55988 7600 1678108 0 0 4 48 614 721 0 0 13 87
0 22 0 55988 7600 1678120 0 0 0 0 501 371 0 0 0 100
0 22 0 56112 7600 1678120 0 0 0 0 465 311 0 0 0 100
0 23 0 56064 7660 1678184 0 0 120 0 488 449 2 1 0 97
0 24 0 43684 7712 1682604 0 0 4416 104 600 1161 2 2 0 97
0 24 0 43692 7712 1682568 0 0 0 0 550 363 0 0 0 100
25 19 0 26712 7752 1696056 0 0 264 5872 763 945 11 7 0 82
26 12 0 16496 7800 1712788 0 0 632 44172 515 4054 38 53 0 9
26 11 0 17012 7804 1712036 0 0 48 69440 1019 8243 38 61 0 1
24 4 0 16884 7704 1709856 0 0 128 107284 2580 3877 32 68 0 0
24 5 0 15908 7696 1713756 0 0 652 54496 810 7612 35 66 0 0
25 0 0 15840 7648 1716956 0 0 4 47380 487 3883 40 60 0 0
26 1 0 16592 7496 1714384 0 0 752 52372 1008 2668 40 60 0 0
26 2 0 15952 7348 1712756 0 0 16 79500 1483 2703 35 65 0 0
25 1 0 15888 7208 1710392 0 0 124 121924 1997 2713 35 65 0 0
25 0 0 16900 7048 1707220 0 0 0 107020 1829 2865 33 67 0 0
25 1 0 16804 6968 1715120 0 0 336 101068 1909 5316 33 65 0 2
29 2 0 15628 6928 1720472 0 0 712 51644 710 6218 38 62 0 0
26 0 0 15360 6708 1718540 0 0 0 78944 997 13772 30 70 1 0
24 5 0 16996 6588 1714992 0 0 20 120532 2318 10112 32 68 0 0
30 5 0 16972 6612 1712060 0 0 276 97880 1756 3526 37 63 0 0
27 3 0 16312 6512 1718500 0 0 20 102096 1981 4503 34 66 0 0
25 16 0 15672 6836 1712320 0 0 1324 29048 761 2265 39 36 0 25
28 8 0 16704 6760 1709436 0 0 100 73980 1172 3956 36 64 0 0
29 5 0 16640 6696 1707612 0 0 0 119576 2498 16484 31 69 0 0
27 8 0 16316 6504 1706384 0 0 12 96948 2601 11700 32 68 0 0
25 4 0 16100 6488 1714172 0 0 52 82184 1682 4525 33 67 0 0
24 20 0 16744 6532 1712988 0 0 532 51036 560 4602 38 62 0 0
29 14 0 17128 6528 1709740 0 0 32 74436 1342 5652 34 66 0 0
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