# echo 1 > /proc/sys/vm/drop_caches ; sync
* Single operation on RAID5 (read/write, like untar for example)
- It starts when the jump of bi/bo occurs.
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 176 6423384 12 151356 0 0 173 212 34 48 1 1 98 0
0 0 176 6421688 12 153004 0 0 16 127 5151 1634 2 1 97 0
0 0 176 6419952 12 154724 0 0 0 89 5205 1691 2 0 98 0
0 0 176 6418216 12 156452 0 0 0 32 5346 1768 2 1 97 0
1 0 176 6323928 12 249380 0 0 50456 0 5350 1854 10 2 82 5
1 0 176 6072840 12 497488 0 0 127696 0 5462 1565 21 5 73 1
1 0 176 5829388 12 737636 0 0 116528 108 5576 1830 22 5 73 0
1 0 176 5639876 12 924496 0 0 97896 98525 6761 2095 15 13 68 4
1 0 176 5439212 12 1122796 0 0 97676 102516 7403 2697 17 14 67 2
1 0 176 5241408 12 1318032 0 0 97668 94740 6460 2059 16 12 71 1
2 0 176 5044000 12 1512528 0 0 97704 98848 8209 2430 17 13 70 1
1 0 176 4845076 12 1708524 0 0 97668 98761 6879 2490 16 13 70 1
* Two of these operations run on two different sets of data.
2 0 176 4631564 12 1917264 0 0 111416 78104 7713 3118 17 12 68 2
2 0 176 4260696 12 2283256 0 0 181736 205732 7670 3028 31 23 45
1
2 0 176 3882464 12 2656564 0 0 195392 177052 7324 3271 31 23 39
8
1 1 176 3535608 12 2997788 0 0 160152 185052 9408 3724 32 25 36
7
0 2 176 3184864 12 3342392 0 0 163220 181252 8392 3582 32 24 37
7
3 1 176 2837420 12 3685484 0 0 170424 169939 9071 3242 30 21 43
5
2 1 176 2449528 12 4066656 0 0 190208 196776 7408 3178 33 25 38
4
3 0 176 2058540 12 4452064 0 0 194992 190408 8630 3230 33 24 39
5
7 0 176 1692204 12 4812832 0 0 176528 185336 8583 3838 32 21 40
6
8 0 176 1302428 12 5195400 0 0 195332 186460 9345 3663 33 25 37
* Three of these operations run on three different sets of data.
2 1 176 910448 12 5580544 0 0 184484 204909 8533 3109 35 25 34 6
2 1 176 487040 12 5997284 0 0 211716 205592 9795 3263 36 24 22 19
2 0 176 40456 12 6437196 0 0 222324 229712 7932 2952 40 29 20 12
6 0 176 45348 12 6433304 0 0 279344 230608 7553 4077 38 29 25 7
3 1 176 44784 12 6434256 0 0 197052 247164 9109 4454 42 30 19 10
3 0 176 44856 12 6433404 0 0 256128 250500 8505 3924 42 31 17 11
7 0 176 43832 12 6435116 0 0 279352 250440 7998 4171 41 31 21 6
2 1 176 43888 12 6434544 0 0 214440 234088 9106 4181 41 29 19 11
5 0 176 45676 12 6433164 0 0 230512 263132 8720 4289 45 30 16 9
5 0 176 45040 12 6433164 0 0 287536 229856 7886 4669 40 30 19 12
8 0 176 46012 12 6432800 0 0 257844 147884 9291 4833 46 24 18 12
9 1 176 46072 12 6432492 0 0 187156 361096 8643 3738 38 35 21 6
Overall the raw speed according to vmstat seems to increase as you add more
load to the server. So I decided to time running three jobs on two parts
of data and compare it with a single job that proceses them all.
Three jobs run con-currently: (2 parts/each):
1- 59.99user 18.25system 2:02.07elapsed 64%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+21000minor)pagefaults 0swaps
2- 59.86user 17.78system 1:59.96elapsed 64%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (21major+20958minor)pagefaults 0swaps
3- 74.77user 22.83system 2:13.30elapsed 73%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (36major+21827minor)pagefaults 0swaps
One job with (6 parts):
1 188.66user 56.84system 4:38.52elapsed 88%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (71major+43245minor)pagefaults 0swaps
Why is running 3 jobs con-currently that take care of two parts each more than
twice as fast than running one job for six parts?
I am using XFS and md/RAID-5, the CFQ scheduler and kernel 2.6.27.4.
Is this more of an md/raid issue ( I am guessing ) than XFS? I remember
reading of some RAID acceleration patches awhile back that were supposed
to boost performance quite a bit, what happened to them?
Justin.
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