Re: [patch 1/21] random fixes

Adam Kropelin (akropel1@rochester.rr.com)
Sun, 11 Aug 2002 20:27:39 -0400


On Sun, Aug 11, 2002 at 11:09:02AM -0700, Andrew Morton wrote:
> Adam Kropelin wrote:
> >
> > On Sun, Aug 11, 2002 at 12:38:19AM -0700, Andrew Morton wrote:
> > > Sorry, but there's a ton of stuff here. It ends up as a 4600 line
> > > diff. Some code dating back to 2.5.24. It's almost all performance
> >
> > Andrew,
> >
> > Nearly all the patches against mm/vmscan.c are failing when applied
> > to the 2.5.31 Linus just released. Are these patches against a
> > slightly older BK rev?
>
> Gee I hope not.
>
> Try getting them from http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.31/,
> or the big rollup http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.31/everything.gz

The big rollup applied fine, thanks.

I did a bit of testing since I've always thought 2.4 (and 2.5) writeout behavior
left something to be desired. Testbed was a SMP x86 (2xPPro-200) with 160 MB
of RAM. I used everyone's favorite 2.5 scapegoat: IDE, with a single not-very-
fast IBM disk. Filesystem was ext3 in data=ordered mode. Test workload was an
inbound (from the point of view of the system under test) FTP transfer of a
600 MB iso image. All test runs were from a clean boot with all unnecessary
services shut down.

Results (average of 4 runs):

2.5.31-akpm: 2m 43s
2.5.31: 2m 33s
2.4.19: 2m 18s

`vmstat 1` shows some differences, expecially with respect to 2.4 vs. 2.5. In
about 40% of the cases when the bo drops to (near) 0, the machine stalled (FTP
transfer halted, vmstat output paused, etc.). With 2.5.31-akpm, the stalls were
about 3-4 seconds in length. With 2.5.31, the stalls were of the same duration,
but slightly less frequent. With 2.4.19, the stalls were very frequent (closer
to 70% of the time bo hit 0), but were only 1-2 seconds in duration.

Below are representative samples of `vmstat 1` for each kernel during the test. (Note that the low cache usage in the 2.5.31 sample is because the snapshot is
from early in the run when the cache is still filling.)

Let me know if I can provide more information...

--Adam

2.5.31-akpm:
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
0 2 1 112 3436 0 140956 0 0 4 15480 5454 400 0 39 60
0 2 1 112 3436 0 140956 0 0 0 7696 1093 69 0 2 98
0 2 1 112 3436 0 140956 0 0 0 6268 1084 85 0 31 69
1 0 2 112 2476 0 142012 0 0 0 4 2863 250 0 23 77
1 0 0 112 3080 0 142080 0 0 0 68 6730 485 0 46 53
0 1 1 112 2940 0 141968 0 0 0 11720 5025 340 1 33 67
0 1 1 112 2936 0 141968 0 0 0 264 1085 45 0 1 99
1 0 1 112 2812 0 142344 0 0 0 52 3104 203 0 18 82
0 0 0 112 3300 0 141972 0 0 0 4 6761 469 1 42 57
1 0 0 112 3492 0 141684 0 0 0 0 6859 495 1 42 56
0 1 1 112 3548 0 141204 0 0 0 15508 4769 328 0 31 69
0 1 1 112 3544 0 141204 0 0 0 2268 1081 63 0 2 98
0 0 0 112 2436 0 142248 0 0 0 56 2006 147 0 10 90
1 0 0 112 2952 0 142328 0 0 0 4 6760 452 1 43 56
1 0 1 112 3432 0 141716 0 0 0 0 6955 464 1 42 57
0 1 1 112 2940 0 141816 0 0 0 15612 4301 262 0 28 72
0 1 1 112 2932 0 141816 0 0 0 588 1095 78 0 2 98
1 0 0 112 2620 0 142660 0 0 0 52 4554 314 1 30 69
1 0 0 112 3420 0 141808 0 0 0 4 6673 465 0 43 57
0 0 0 112 2628 0 142456 0 0 0 4 6931 491 1 44 55

2.5.31:
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 0 118940 0 28240 0 0 4 0 4171 256 1 21 78
1 0 0 0 110904 0 36036 0 0 0 0 8937 590 1 53 46
1 0 0 0 103260 0 43452 0 0 0 0 8558 559 1 50 49
0 0 0 0 97100 0 49424 0 0 0 0 6919 460 1 41 58
0 1 1 0 96048 0 50104 0 0 0 21036 1798 67 0 9 90
0 1 1 0 96044 0 50104 0 0 0 3888 1087 55 0 2 98
0 1 1 0 96044 0 50104 0 0 0 0 1081 65 0 1 99
1 0 0 0 91516 0 54544 0 0 0 72 5305 352 0 33 67
0 0 0 0 85392 0 60560 0 0 0 0 6972 458 0 44 56
0 0 1 0 79344 0 66476 0 0 0 10788 6384 3173 1 48 50
1 0 0 0 73296 0 72416 0 0 0 44 6705 1392 1 49 50
0 0 0 0 67156 0 78444 0 0 0 0 6975 475 1 62 37
1 0 0 0 61392 0 84104 0 0 0 0 6603 442 0 37 62
0 1 1 0 55272 0 90016 0 0 0 15500 6940 451 1 42 57
0 1 1 0 55272 0 90016 0 0 0 7696 1123 13 0 3 97

2.4.19:
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 0 4384 2124 140132 0 0 0 52 6961 645 0 54 45
1 0 0 0 4372 2132 140024 0 0 0 0 6994 653 1 50 50
0 1 1 0 4360 2136 139916 0 0 0 3956 6189 577 1 44 55
0 1 1 0 4360 2136 139916 0 0 0 8196 223 14 0 2 97
0 0 1 0 4344 2140 139908 0 0 0 6080 1189 90 0 9 91
0 1 1 0 4440 2140 139764 0 0 4 7296 5902 557 0 43 57
1 0 0 0 4360 2144 140044 0 0 0 56 3515 307 0 29 71
0 1 1 0 4468 2144 139936 0 0 0 4036 5672 519 0 42 57
0 1 1 0 4468 2144 139936 0 0 0 7960 220 14 0 1 99
1 0 1 0 4464 2144 139980 0 0 0 5160 2073 178 0 17 82
1 0 0 0 4396 2164 140092 0 0 0 3148 6965 656 1 51 48
1 0 0 0 4396 2164 140068 0 0 0 0 7193 656 1 44 54
0 2 1 0 4384 2164 139996 0 0 0 5848 4923 454 1 37 62
0 2 1 0 4384 2164 139996 0 0 0 6148 222 10 0 0 99
1 0 1 0 4400 2168 139900 0 0 0 7400 2961 258 0 24 75
1 0 0 0 4464 2184 140004 0 0 0 52 7076 659 1 51 48
1 0 0 0 4452 2184 139936 0 0 0 0 6960 638 0 54 46
0 1 2 0 4404 2188 139932 0 0 0 5968 4332 399 0 30 69
0 1 1 0 4404 2188 139932 0 0 0 4804 222 12 0 1 99

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