shm bugs revisited

Christoph Rohland hans-christoph.rohland en sap.com
Mar Ene 25 17:21:34 CST 2000


Hi folks,

I am still trying to hunt down the shm bugs I am experiencing under
high smp load. I reported kernel oopses during swapping.

But I now realized that errors occur without even swapping. My test
program shows inconsistent data on rereading the segment.

I am running the appended test program on an 8GB 8way with
2.3.41-pre2+tmp/smp-2.3.41-A1:

#ipctst 10 666400000 10 30 20&
#vmstat 5
   procs                      memory    swap          io     system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
10  0  0      0 2876192   2320   9804   0   0     3     1   16   183   0   3  97
 9  1  1      0 1017356   2320   9804   0   0     0     1  125 62010   0  90   9
 9  1  0      0 660392   2320   9804   0   0     0     0  111 61688   1  86  13
 5  5  0      0 1036448   2320   9804   0   0     0     0  117 87875   3  85  13
 5  5  0      0 507900   2320   9804   0   0     0     0  115 106577   0  64  35
 7  3  0      0 223152   2320   9804   0   0     0     0  108 86321   3  79  18
 8  2  0      0 3488412   2320   9804   0   0     0     0  113 82936   3  84  14
 5  5  0      0 3649372   2320   9804   0   0     0     0  109 102095   2  70  27
*p(0) != p(1458691561)
 9  1  0      0 2909576   2320   9804   0   0     0     0  107 79827   2  83  15
 8  2  0      0 3618740   2320   9804   0   0     0     0  122 101344   4  74  22
 5  5  0      0 3999636   2320   9804   0   0     0     0  110 76780   2  77  21
 8  2  0      0 3271184   2320   9804   0   0     0     0  114 62834   1  78  20
# ipcs -um

------ Shared Memory Status --------
segments allocated 9
pages allocated 1464264
pages resident  1245454
pages swapped   0
Swap performance: 0 attempts     0 successes

## vmstat 5                       
   procs                      memory    swap          io     system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
 8  2  0      0 3625700   2332   9808   0   0     1     0   14  6848   2  57  41
 8  2  0      0 2554328   2332   9808   0   0     0     0  114 83047   2  83  15
10  0  0      0 3040068   2332   9808   0   0     0     1  111 79825   3  82  16
 6  4  0      0 2791848   2332   9808   0   0     0     0  107 85891   3  84  13
*p(0) != p(1623759691)
 7  3  0      0 2316364   2332   9808   0   0     0     0  108 99128   2  68  30
 7  3  0      0 2316364   2332   9808   0   0     0     0  107 102336   2  67  31
 7  3  0      0 2061568   2332   9808   0   0     0     0  108 90342   3  75  21
 6  4  0      0 1793400   2332   9808   0   0     0     0  107 87724   2  82  16
*p(-115) != p(1735206285)
*p(116) != p(1737201524)
*p(73) != p(1738074185)
*p(116) != p(1738250356)
*p(-26) != p(1738717414)
*p(29) != p(1738942749)
*p(57) != p(1739057465)
*p(108) != p(1739266412)
*p(-116) != p(1739397516)
*p(-71) != p(1739581881)
*p(-7) != p(1739844089)
*p(84) != p(1740216916)
*p(-115) != p(1740450445)
*p(-89) != p(1740556967)
*p(-50) != p(1740716750)
*p(2) != p(1740929794)
*p(8) != p(1074946056)
*p(71) != p(1075204167)
*p(67) != p(1076236611)
*p(96) != p(1076355424)
*p(-113) != p(1076547983)
*p(-86) != p(1076658602)
*p(-1) != p(1077006847)
*p(53) != p(1077228085)
*p(-118) != p(1077576330)
*p(-58) != p(1077822150)
*p(-33) != p(1077924575)
*p(85) != p(1078408021)
*p(118) != p(1078543222)
*p(-122) != p(1078608774)
*p(-55) != p(1078883273)
*p(-19) != p(1079030765)
*p(16) != p(1079174160)
*p(44) != p(1079288876)
*p(108) != p(1079551084)
*p(-52) != p(1079944396)
*p(-44) != p(1079977172)
*p(-21) != p(1080071403)
*p(44) != p(1080337708)
*p(-116) != p(1080731020)
*p(-63) != p(1080948161)
*p(16) != p(1081271824)
*p(44) != p(1081386540)
*p(57) != p(1081439801)
*p(67) != p(1081480771)
*p(84) != p(1081550420)
*p(-118) != p(1081771658)
 5  4  0      0 3458140   2344   9868   0   0    10     0  132 89677   4  78  18
 6  3  0      0 2614876   2344   9868   0   0     0     6  111 97286   1  63  36
 7  2  0      0 395560   2344   9868   0   0     0     0  106 80362   3  66  31
 5  4  0      0 3948976   2344   9868   0   0     0     0  174 126050   2  66  33
 8  1  0      0 3852856   2344   9868   0   0     0     0  108 87175   2  72  25
 8  1  0      0 3560500   2344   9868   0   0     0     0  107 71922   3  77  20
 6  3  0      0 3440356   2344   9868   0   0     0     0  132 105096   2  59  39
 7  2  0      0 2969508   2344   9868   0   0     0     0  107 89670   2  65  33
 9  0  0      0 2864612   2344   9868   0   0     0     0  108 83785   4  75  21
shmctl IPC_RMID: Invalid argument
 9  0  0      0  35372   2344   9868   0   0     0     0  117 79154   4  82  14
 7  2  0      0 546528   2344   9868   0   0     0     0  110 80181   2  75  23
 7  2  0      0 3737452   2344   9868   0   0     0     0  112 77312   3  81  16
 4  5  0      0 3811436   2344   9868   0   0     0     0  111 67178   2  75  23
#

(vmstat wraps at 4GB free, it's an old version)

Greetings
		Christoph

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