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SubjectREPORT: NFS and ReiserFS very high latencies, with low-latency and preempt applied
Date
Hi all,
Linux becomes somehow unusable when I edited sound files and also
during NFS copy. I've noticed the same effects also during i/o loads, for
example when closing kmail after I deleted some messages.

I was also surprised that when doing just memory operations in kwave, the X
server also is blocked and after exiting kwave, kmail just died.

I send this reports just in case is useful. Sorry by the ugly style/grammar,
I didn't have much time to improve it.

Regards,

--
ricardo
"I just stopped using Windows and now you tell me to use Mirrors?"
- said Aunt Tillie, just before downloading 2.5.3 kernel.



-----------------------------
I've noticed that my system, a P3, 1Ghz, 2.4.18+low-latency+preempt patches
applied (and enabled) did suffered of very high latencies due to disk and
_memory_ operations when editing wav files with kwave.

_Whithout_ the patches applied the kernel blocks even when reading a wav file
from kwave, after applying the patches the response was much better. _But_ it
was suffering very large latencies when editing sund, for example deleting
fragments or changing zoom. The X server blocked during seconds, even for
updating the pointer position.

I did another test, copying big files (60-90 MB) from a NFS client via 100mbps
ethernet. The client was a 2.4.19-pre4 (PPC on a iBook 500 Mhz). cp was executed
from the client. Every few seconds even the mouse was blocked.

The vmstat of the NFS copy is as follows (it started and ended almost at the
same time as the cp):

gallir@antoli:~$ vmstat 3
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
1 0 0 86800 226312 26828 118812 0 0 9 22 195 194 2 0 97
0 0 2 86800 212080 26936 132856 0 0 0 63 4059 2368 1 17 82
0 0 1 86800 181260 26968 163436 0 0 0 0 8587 4232 0 40 60
0 0 1 86800 151192 27092 193380 0 0 0 55 8435 4138 0 37 63
0 0 1 86800 121060 27124 223464 0 0 0 0 8558 4183 0 37 63
0 0 2 86800 90536 27252 253856 0 0 0 64 8518 4209 0 34 66
0 0 1 86800 67836 27376 276416 0 0 1 61 6403 3229 0 32 68
0 0 1 86800 39916 27408 304304 0 0 0 0 7925 3872 0 38 62
0 0 2 86800 16952 27532 327144 0 0 0 336 6582 3277 0 32 68
0 0 2 86800 16716 27532 327380 0 0 0 2504 594 970 0 2 98
0 0 1 86948 4344 24600 345332 0 59 0 4825 5541 4156 1 27 72
0 0 3 87056 4416 24244 350796 0 4 0 26520 2222 2974 1 13 86
2 0 3 87156 4444 19524 360172 0 24 0 2264 7435 7035 7 40 53
1 0 1 87156 4460 17548 362208 0 0 0 60 6933 7437 6 32 62
1 0 3 87156 4336 13944 366000 0 0 0 0 8483 8102 4 50 46
1 0 2 87196 4336 10124 370384 0 0 0 8040 6417 6668 6 35 59
3 0 3 87196 4440 8400 372220 0 0 0 16776 4567 5760 6 26 68
1 0 1 87196 4420 8396 372152 0 0 0 7081 4502 5736 2 23 76
1 0 0 87196 4412 8416 372256 0 0 0 0 7018 7447 9 41 51
2 0 1 87196 4424 8436 372224 0 0 0 1507 8450 8037 5 50 46
2 0 2 87196 4400 8520 372180 0 0 0 15876 4346 5856 7 23 70
2 0 1 87196 4412 8548 372136 0 0 0 0 7972 7891 4 40 56
1 0 2 87196 4396 8564 372120 0 0 0 11304 6112 6835 10 35 56
1 0 3 87196 4448 8564 372072 0 0 0 28163 1538 4268 1 8 91
0 0 2 87196 4324 8540 372036 0 0 0 3419 6686 3508 0 31 69
0 0 1 87196 4412 8668 371812 0 0 0 61 8458 4342 0 40 60
0 0 1 87196 4368 8544 372072 0 0 0 0 8825 6344 3 40 57
1 0 1 87676 4396 8612 372256 0 177 0 243 8482 5064 1 39 59
1 0 3 87676 4440 8624 372132 0 13 0 20252 3989 4229 1 23 76
0 0 0 87676 4444 8696 372056 0 0 0 2763 375 1463 1 1 98
0 0 0 87676 4428 8712 372056 0 0 0 8 162 385 0 0 100
0 0 0 87676 4428 8712 372056 0 0 0 0 161 386 0 0 100

The files copyied during the test were:

-rw-r--r-- 1 root gallir 10899212 Apr 4 14:49 track01.cdda.wav
-rw-r--r-- 1 root gallir 33360812 Apr 4 14:49 track02.cdda.wav
-rw-r--r-- 1 root gallir 50097644 Apr 4 14:49 track03.cdda.wav
-rw-r--r-- 1 root gallir 41392892 Apr 4 14:49 track04.cdda.wav
-rw-r--r-- 1 root gallir 65195132 Apr 4 14:49 track05.cdda.wav
-rw-r--r-- 1 root gallir 67041452 Apr 4 14:49 track06.cdda.wav
-rw-r--r-- 1 root gallir 54879260 Apr 4 14:49 track07.cdda.wav
-rw-r--r-- 1 root gallir 9285740 Apr 4 14:49 track08.cdda.wav
-rw-r--r-- 1 root gallir 55702460 Apr 4 14:49 track09.cdda.wav
-rw-r--r-- 1 root gallir 51821660 Apr 4 14:50 track10.cdda.wav
-rw-r--r-- 1 root gallir 59940764 Apr 4 14:50 track11.cdda.wav
-rw-r--r-- 1 root gallir 52945916 Apr 4 14:50 track12.cdda.wav
-rw------- 1 root gallir 56328192 Apr 4 14:50 track13.cdda.wav

After the files were copyed, I edited one of them (track05.cdda.wav).

KWAVE VMSTAT
------------
gallir@antoli:~/tmp$ vmstat 3
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
0 0 0 87676 4412 9644 368252 0 0 9 24 198 197 2 0 97
0 0 0 87676 4396 9660 368252 0 0 0 11 382 1740 1 0 98
# read file track05.wav (64 MB) starts here
1 0 0 87676 4488 9796 367348 31 0 184 41 407 2002 8 2 90
3 0 0 87676 4432 9836 367352 0 0 1 24 441 2465 8 1 92
2 0 0 87804 4520 9728 302820 31 16 357 133 221 1211 69 29 2
2 0 0 87804 4524 9728 302692 21 0 1387 0 202 256 98 2 0
9 0 0 87804 4472 9744 302692 11 0 1461 8 214 148 96 4 1
2 0 0 87804 4468 9744 302692 11 0 1461 0 210 148 97 3 0
8 0 0 87804 4492 9672 302636 21 0 1131 0 194 145 97 2 1
8 0 0 87804 4504 9672 302636 11 0 1547 0 205 153 95 5 0
6 0 0 87804 4460 9672 302636 0 0 1280 0 200 146 96 4 0
7 0 0 87804 4472 9672 302636 0 0 1280 0 206 140 98 2 0
8 0 0 87804 4472 9672 302636 0 0 1536 0 212 154 96 4 0
2 0 0 87804 4392 9672 302764 0 0 1237 0 203 143 97 3 0
2 0 0 87804 4456 9672 302636 11 0 1419 5 213 152 98 2 0
3 0 0 87804 4488 9672 302636 0 0 1280 0 204 142 98 2 0
3 0 0 87804 4452 9672 302636 0 0 1451 0 214 152 96 4 0
7 0 0 87804 4448 9672 302636 0 0 1024 0 195 140 97 3 0
6 0 0 87804 4468 9672 302636 0 0 1536 0 210 152 96 4 0
4 0 0 87804 4448 9576 302732 0 0 1280 0 206 147 96 4 0
0 0 0 87804 5276 9576 302644 21 0 716 0 184 2501 82 5 13
0 0 0 87804 5208 9644 302644 0 0 0 43 325 1273 0 3 97
0 0 0 87804 5192 9660 302644 0 0 0 8 375 421 51 1 48
1 0 0 87804 4360 9640 303584 0 0 1 0 348 1580 2 10 88
1 0 0 87804 4456 9792 303284 0 0 8 77 326 1883 28 8 64
2 0 0 87804 51996 9792 279484 0 0 12 0 290 1615 29 3 68
4 0 1 87804 52000 9792 279484 0 0 0 12399 589 1010 33 6 61
2 0 0 87804 48484 9880 279484 0 0 0 935 408 1580 17 2 81
0 0 0 87804 51860 9896 279484 0 0 0 9 453 2740 13 2 85
0 0 0 87804 51852 9896 279484 0 0 0 0 273 1134 20 1 79
0 0 0 87804 51836 9912 279484 0 0 0 8 329 1483 2 4 94
0 0 0 87804 33036 9912 279492 0 0 3 0 347 1798 13 3 83
# delete selection
2 0 1 87804 31740 9912 279492 0 0 0 15891 584 1675 37 11 52
1 0 0 87804 29304 10000 279492 0 0 0 68 565 2640 95 5 0
5 0 0 87804 26968 10016 279492 0 0 0 8 311 1561 99 1 0
1 0 0 87804 24408 10016 279492 0 0 0 0 262 1067 97 3 0
1 0 0 87804 21668 10032 280772 0 0 0 9 258 1025 96 4 0
2 0 0 87804 19592 10036 282820 0 0 0 0 371 1748 94 6 0
# save file
2 0 1 87804 17552 10036 284868 0 0 0 16413 823 3017 86 14 0
2 0 1 87804 15508 10040 286916 0 0 0 15073 829 3299 84 16 0
1 0 1 87804 13492 10040 288908 0 0 0 15233 558 1451 90 10 0
1 0 0 87804 13912 10108 288908 0 0 0 12271 716 2698 19 4 77
0 0 0 87804 13908 10108 288908 0 0 0 0 519 2622 2 1 98
1 0 0 87804 13892 10124 288908 0 0 0 15 438 2134 3 2 96
0 0 0 87804 13892 10124 288908 0 0 0 0 413 2215 4 6 89
2 0 0 87804 13368 10152 289192 0 0 37 9 387 2263 8 2 90
1 0 0 87804 9900 10256 292260 41 0 60 107 300 1996 23 4 73
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
2 0 0 87804 4356 10256 297924 0 0 0 0 268 2928 88 12 0
# save file
1 0 0 87804 4448 10228 297732 43 0 43 37 167 2382 89 11 0
1 0 0 87804 4408 10244 297676 29 0 29 0 164 2394 89 11 0
2 0 0 87804 4508 10336 297632 11 0 11 59 378 2175 16 4 80
0 0 0 87804 173012 10436 200736 0 0 9 64 380 2254 21 7 72


After exiting kwave, kmail suddenly just DIED.

--------------------------------------------
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