After some run time (about 100GB in), 2.6.18 continues to write at close to 250MB/s per filesystem (as per original trace). 2.6.20-rc3 with dirty_ratio = 40 does: $ vmstat 5 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 7 0 90540 8 15796472 0 0 10 164413 734 6124 0 51 23 25 2 7 0 91060 8 15773864 0 0 0 558089 3780 27825 1 48 12 40 8 8 0 91808 8 15764172 0 0 0 692855 3343 25813 0 63 8 29 4 9 0 86604 8 15770876 0 0 6 670767 3605 32657 1 63 8 28 1 11 0 83840 8 15775184 0 0 0 666833 3398 31701 0 64 3 33 3 9 0 82300 8 15776156 0 0 2 616678 3939 37617 1 58 10 32 11 6 0 90640 8 15771528 0 0 2 696310 3395 38654 0 67 5 28 5 9 0 92412 8 15771872 0 0 2 585962 3453 32651 1 54 14 32 5 9 0 90452 8 15766020 0 0 5 583086 3670 32937 0 55 7 38 2 9 0 87980 8 15763964 0 0 1 681694 3525 30906 1 64 9 26 3 8 0 86664 8 15761044 0 0 2 650998 3677 25797 0 61 6 32 6 8 0 86804 8 15759052 0 0 0 715986 3317 25729 1 69 11 20 3 10 0 84240 8 15765944 0 0 0 673761 3528 25241 0 64 7 29 7 10 0 89916 8 15763700 0 0 5 664583 3506 27555 1 63 7 30 1 8 0 82896 8 15814824 0 0 2 519892 3456 24579 0 49 23 29 3 7 0 88276 8 15809844 0 0 1 415687 3093 15203 0 29 50 20 3 8 0 88324 8 15778956 0 0 0 589647 3370 30624 0 52 13 35 2 8 0 91776 8 15775764 0 0 0 609689 3506 32780 0 56 11 33 3 9 0 85604 8 15778512 0 0 0 656673 3573 37672 0 64 5 31 3 10 0 85676 8 15785708 0 0 5 644915 3746 39503 1 63 6 31 5 8 0 89700 8 15775952 0 0 2 680001 3510 38927 0 65 8 27 0 8 0 82332 8 15814516 0 0 1 638288 3499 36999 0 63 6 30 3 8 0 88748 8 15767756 0 0 0 535037 3797 26778 0 44 9 47 8 9 0 86620 8 15773060 0 0 0 581291 3556 27902 1 54 9 37 3 11 0 93708 8 15759696 0 0 6 647017 3714 33242 0 61 6 32 3 9 0 90172 8 15759952 0 0 0 716961 3345 35311 1 70 7 23 3 9 0 90040 8 15763172 0 0 0 655000 3652 31259 0 61 11 27 4 8 0 87176 8 15764384 0 0 1 643515 3668 32440 0 62 5 32 1 10 0 83812 8 15786040 0 0 0 650601 3605 33809 0 64 8 28 5 9 0 82760 8 15805612 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