Re: [BUG] RAID sub system

Roy Sigurd Karlsbakk (roy@karlsbakk.net)
Thu, 13 Dec 2001 20:14:53 +0100 (CET)


> > > do did you actually try this with a bunch of parallel dd's?
> >
> > I just did now. Same result:
> >
> > # vmstat 2
> > r b w swpd free buff cache si so bi bo in cs us sy id
> > 0 200 1 1676 3200 3012 786004 0 292 42034 298 791 745 4 29 67
> > 0 200 1 1676 3308 3136 785760 0 0 44304 0 748 758 3 15 82
> > 0 200 1 1676 3296 3232 785676 0 0 44236 0 756 710 2 23 75
> > 0 200 1 1676 3304 3356 785548 0 0 38662 70 778 791 3 19 78
> > 0 200 1 1676 3200 3456 785552 0 0 33536 0 693 594 3 13 84
> > 1 200 0 1676 3224 3528 785192 0 0 35330 24 794 712 3 16 81
> > 0 200 0 1676 3304 3736 784324 0 0 30524 74 725 793 12 14 74
> > 0 200 0 1676 3256 3796 783664 0 0 29984 0 718 826 4 10 86
> > 0 200 0 1676 3288 3868 783592 0 0 25540 152 763 812 3 17 80
> > 0 200 0 1676 3276 3908 783472 0 0 22820 0 693 731 0 7 92
> > 0 200 0 1676 3200 3964 783540 0 0 23312 6 759 827 4 11 85
> > 0 200 0 1676 3308 3984 783452 0 0 17506 0 687 697 0 11 89
> > 0 200 0 1676 3388 4012 783888 0 0 14512 0 671 638 1 5 93
> > 0 200 0 2188 3208 4048 784156 0 512 16104 548 707 833 2 10 88
> > 0 200 0 3468 3204 4048 784788 0 66 8220 66 628 662 0 3 96
> > 0 200 0 3468 3296 4060 784680 0 0 1036 6 687 714 1 6 93
> > 0 200 0 3468 3316 4060 784668 0 0 1018 0 613 631 1 2 97
> > 0 200 0 3468 3292 4060 784688 0 0 1034 0 617 638 0 3 97
> > 0 200 0 3468 3200 4068 784772 0 0 1066 6 694 727 2 4 94
>
> so help me out here a little. the first dozen or so lines look good,
> but obviously slowing down (which is a little odd). then at line -6,
> the VM freaks, tries swapping out, and everything goes to sleep.
> it's the going to sleep you're worried about, right?

Yes. I really need all available I/O here, not nasty bugs.

hm

trying to time the problem:

# init 6
...
# free
total used free shared buffers cached
Mem: 899712 75576 824136 0 4836 29408
-/+ buffers/cache: 41332 858380
Swap: 674720 0 674720
# dd-test ; vmstat -n 2 > vmstat &
# tail -f vmstat
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
0 200 0 0 767440 5036 36616 0 0 565 153 4337 276 9 20 71
0 200 0 0 733012 5412 69180 0 0 16324 0 603 628 0 6 94
0 200 0 0 667196 5428 132408 0 0 31488 56 678 530 1 12 87
0 200 0 0 600792 5580 196472 0 0 32114 0 683 536 2 10 88
0 200 0 0 528956 5616 265956 0 0 34708 30 678 482 0 15 85
0 200 0 0 451496 5724 340508 0 0 37338 0 724 640 1 16 82
0 200 0 0 383020 5936 406512 0 0 33096 8 699 689 2 11 87
0 200 0 0 301368 6032 485432 0 0 39464 0 726 522 2 15 83
0 200 0 0 216412 6124 567552 0 0 41092 0 698 613 2 17 81
0 200 0 0 131364 6248 649732 0 0 41162 8 722 701 2 18 80
0 200 0 0 52740 6372 725696 0 0 38028 0 721 461 2 14 84
0 200 1 2676 3264 2944 778932 0 308 44816 380 766 804 0 23 76
0 200 1 2676 3272 3032 778844 0 0 45562 0 764 642 2 17 81
0 200 1 2676 3292 3136 778712 0 0 39156 0 721 767 1 20 78
0 200 1 2676 3264 3260 778620 0 0 40664 8 738 624 2 11 86
0 200 0 2676 3212 3368 778480 0 0 37056 0 727 614 1 15 84
0 200 1 2676 3228 3464 778468 0 0 32052 8 654 743 2 12 86
0 200 1 2676 3196 3492 778472 0 2 30882 2 713 721 0 12 88
0 200 1 2676 3220 3556 778368 0 0 26490 0 698 739 1 10 89
0 200 0 2676 3224 3640 778212 0 0 25194 36 709 706 0 11 89
0 200 0 2676 3304 3692 778136 0 0 20998 0 678 732 1 6 93
0 200 0 2676 3272 3748 778108 0 0 19734 16 689 768 1 11 88
0 200 1 2676 3236 3780 778060 0 0 13708 0 644 748 0 6 94
0 200 0 2676 3196 3800 778076 0 0 9492 0 629 644 0 8 92
0 200 0 2676 3308 3828 778020 0 0 12978 8 664 727 1 6 93
0 200 0 2676 3512 3848 777716 0 14 11130 14 664 698 1 6 93
0 200 0 2804 3256 3860 777896 0 870 7074 878 677 674 0 3 96
0 200 0 2804 3288 3860 777856 0 0 1068 0 625 665 1 3 96
0 200 0 2804 3320 3868 777816 0 16 1068 24 627 667 1 2 97
0 200 0 2804 3212 3868 777928 0 84 1080 84 600 671 1 2 97

...and so on

This gives a total read of a little less than 800MB before giving up. Is
there a cache timeout that needs to be set any lower?

roy

--
Roy Sigurd Karlsbakk, MCSE, MCNE, CLS, LCA

Computers are like air conditioners. They stop working when you open Windows.

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