inaccurate migration cost calculation?
From: Dave Jones
Date: Tue Jan 02 2007 - 18:57:51 EST
Across different boots using the same 2.6.19 kernel on a quad-core xeon
I see huge variance in the migration_cost being reported during boot.
-migration_cost=39,3940
+migration_cost=25,4941
This CPU has a very large cache which could be key here...
L1 Instruction cache: 32KB, 8-way associative. 64 byte line size.
L1 Data cache: 32KB, 8-way associative. 64 byte line size.
L3 unified cache: 4MB, 16-way associative. 64 byte line size.
Here's the output of migration_debug=1 for another two boots..
-> [0][1][ 65536] 0.0 [ 0.0] (1): ( 42507 21253)
-> [0][1][ 72817] 0.0 [ 0.0] (1): ( 46350 12548)
-> [0][1][ 80907] 0.0 [ 0.0] (1): ( 58571 12384)
-> [0][1][ 89896] 0.0 [ 0.0] (1): ( 57738 6608)
-> [0][1][ 99884] 0.0 [ 0.0] (1): ( 60743 4806)
-> [0][1][ 110982] 0.0 [ 0.0] (1): ( 67393 5728)
-> [0][1][ 123313] 0.0 [ 0.0] (1): ( 72416 5375)
-> [0][1][ 137014] 0.0 [ 0.0] (1): ( 73890 3424)
-> [0][1][ 152237] 0.0 [ 0.0] (1): ( 75735 2634)
-> [0][1][ 169152] 0.0 [ 0.0] (1): ( 91870 9384)
-> [0][1][ 187946] 0.0 [ 0.0] (1): ( 88701 6276)
-> [0][1][ 208828] 0.1 [ 0.1] (1): ( 102106 9840)
-> [0][1][ 232031] 0.1 [ 0.1] (1): ( 112433 10083)
-> [0][1][ 257812] 0.1 [ 0.1] (1): ( 118441 8045)
-> [0][1][ 286457] 0.1 [ 0.1] (1): ( 126302 7953)
-> [0][1][ 318285] 0.1 [ 0.1] (1): ( 135442 8546)
-> [0][1][ 353650] 0.1 [ 0.1] (1): ( 165438 19271)
-> [0][1][ 392944] 0.1 [ 0.1] (1): ( 196143 24988)
-> [0][1][ 436604] 0.1 [ 0.1] (1): ( 180626 20252)
-> [0][1][ 485115] 0.2 [ 0.2] (1): ( 209017 24321)
-> [0][1][ 539016] 0.2 [ 0.2] (1): ( 231664 23484)
-> [0][1][ 598906] 0.2 [ 0.2] (1): ( 277569 34694)
-> [0][1][ 665451] 0.2 [ 0.2] (1): ( 276351 17956)
-> [0][1][ 739390] 0.3 [ 0.3] (1): ( 318707 30156)
-> [0][1][ 821544] 0.3 [ 0.3] (1): ( 382865 47157)
-> [0][1][ 912826] 0.3 [ 0.3] (1): ( 398566 31429)
-> [0][1][1014251] 0.4 [ 0.4] (1): ( 441757 37310)
-> [0][1][1126945] 0.5 [ 0.5] (1): ( 516100 55826)
-> [0][1][1252161] 0.5 [ 0.5] (1): ( 543549 41637)
-> [0][1][1391290] 0.6 [ 0.6] (1): ( 603068 50578)
-> [0][1][1545877] 0.6 [ 0.6] (1): ( 637083 42296)
-> [0][1][1717641] 0.8 [ 0.8] (1): ( 800596 102904)
-> [0][1][1908490] 0.8 [ 0.8] (1): ( 856786 79547)
-> [0][1][2120544] 0.9 [ 0.9] (1): ( 919895 71328)
-> [0][1][2356160] 0.9 [ 0.9] (1): ( 973085 62259)
-> [0][1][2617955] 1.1 [ 1.1] (1): ( 1114043 101608)
-> [0][1][2908838] 1.2 [ 1.2] (1): ( 1219850 103707)
-> [0][1][3232042] 1.3 [ 1.3] (1): ( 1327969 105913)
-> [0][1][3591157] 1.4 [ 1.4] (1): ( 1463296 120620)
-> [0][1][3990174] 1.6 [ 1.6] (1): ( 1630438 143881)
-> [0][1][4433526] 1.7 [ 1.7] (1): ( 1729272 121357)
-> [0][1][4926140] 1.7 [ 1.7] (1): ( 1733278 62681)
-> [0][1][5473488] 1.9 [ 1.9] (1): ( 1958482 143942)
-> [0][1][6081653] 1.8 [ 1.9] (1): ( 1872926 114749)
-> [0][1][6757392] 1.7 [ 1.9] (1): ( 1713013 137331)
-> [0][1][7508213] 1.3 [ 1.9] (1): ( 1392757 228793)
-> [0][1][8342458] 1.1 [ 1.9] (1): ( 1116378 252586)
-> found max.
[0][1] working set size found: 5473488, cost: 1958482
-> [0][2][ 65536] 0.0 [ 0.0] (0): ( 9187 4593)
-> [0][2][ 72817] 0.0 [ 0.0] (0): ( 13719 4562)
-> [0][2][ 80907] 0.0 [ 0.0] (0): ( 8008 5136)
-> [0][2][ 89896] 0.0 [ 0.0] (0): ( 7924 2610)
-> [0][2][ 99884] 0.0 [ 0.0] (0): ( 2640 3947)
-> found max.
[0][2] working set size found: 72817, cost: 13719
migration: max_cache_size: 0, cpu: 2666 MHz:
migration_cost=27,3916
migration: 0 seconds
-> [0][1][ 65536] 0.0 [ 0.0] (1): ( 36355 18177)
-> [0][1][ 72817] 0.0 [ 0.0] (1): ( 49107 15464)
-> [0][1][ 80907] 0.0 [ 0.0] (1): ( 57124 11740)
-> [0][1][ 89896] 0.0 [ 0.0] (1): ( 57766 6191)
-> [0][1][ 99884] 0.0 [ 0.0] (1): ( 72324 10374)
-> [0][1][ 110982] 0.0 [ 0.0] (1): ( 80125 9087)
-> [0][1][ 123313] 0.0 [ 0.0] (1): ( 74042 7585)
-> [0][1][ 137014] 0.0 [ 0.0] (1): ( 78227 5885)
-> [0][1][ 152237] 0.0 [ 0.0] (1): ( 80157 3907)
-> [0][1][ 169152] 0.0 [ 0.0] (1): ( 88881 6315)
-> [0][1][ 187946] 0.0 [ 0.0] (1): ( 99344 8389)
-> [0][1][ 208828] 0.1 [ 0.1] (1): ( 104998 7021)
-> [0][1][ 232031] 0.1 [ 0.1] (1): ( 113660 7841)
-> [0][1][ 257812] 0.1 [ 0.1] (1): ( 124690 9435)
-> [0][1][ 286457] 0.1 [ 0.1] (1): ( 135835 10290)
-> [0][1][ 318285] 0.1 [ 0.1] (1): ( 153135 13795)
-> [0][1][ 353650] 0.1 [ 0.1] (1): ( 145024 10953)
-> [0][1][ 392944] 0.2 [ 0.2] (1): ( 215998 40963)
-> [0][1][ 436604] 0.2 [ 0.2] (1): ( 212086 22437)
-> [0][1][ 485115] 0.2 [ 0.2] (1): ( 250632 30491)
-> [0][1][ 539016] 0.2 [ 0.2] (1): ( 221014 30054)
-> [0][1][ 598906] 0.2 [ 0.2] (1): ( 281687 45363)
-> [0][1][ 665451] 0.2 [ 0.2] (1): ( 296981 30328)
-> [0][1][ 739390] 0.3 [ 0.3] (1): ( 351999 42673)
-> [0][1][ 821544] 0.4 [ 0.4] (1): ( 413272 51973)
-> [0][1][ 912826] 0.4 [ 0.4] (1): ( 402094 31575)
-> [0][1][1014251] 0.4 [ 0.4] (1): ( 461726 45603)
-> [0][1][1126945] 0.5 [ 0.5] (1): ( 504549 44213)
-> [0][1][1252161] 0.5 [ 0.5] (1): ( 570889 55276)
-> [0][1][1391290] 0.6 [ 0.6] (1): ( 637668 61027)
-> [0][1][1545877] 0.6 [ 0.6] (1): ( 660241 41800)
-> [0][1][1717641] 0.8 [ 0.8] (1): ( 820951 101255)
-> [0][1][1908490] 0.8 [ 0.8] (1): ( 860249 70276)
-> [0][1][2120544] 0.9 [ 0.9] (1): ( 947017 78522)
-> [0][1][2356160] 0.9 [ 0.9] (1): ( 999742 65623)
-> [0][1][2617955] 1.1 [ 1.1] (1): ( 1152233 109057)
-> [0][1][2908838] 1.2 [ 1.2] (1): ( 1247362 102093)
-> [0][1][3232042] 1.3 [ 1.3] (1): ( 1371438 113084)
-> [0][1][3591157] 1.5 [ 1.5] (1): ( 1518791 130218)
-> [0][1][3990174] 1.6 [ 1.6] (1): ( 1621385 116406)
-> [0][1][4433526] 1.7 [ 1.7] (1): ( 1775523 135272)
-> [0][1][4926140] 1.7 [ 1.7] (1): ( 1784080 71914)
-> [0][1][5473488] 1.9 [ 1.9] (1): ( 1970125 128979)
-> [0][1][6081653] 1.9 [ 1.9] (1): ( 1926772 86166)
-> [0][1][6757392] 1.7 [ 1.9] (1): ( 1722660 145139)
-> [0][1][7508213] 1.4 [ 1.9] (1): ( 1405442 231178)
-> [0][1][8342458] 1.1 [ 1.9] (1): ( 1107804 264408)
-> found max.
[0][1] working set size found: 5473488, cost: 1970125
-> [0][2][ 65536] 0.0 [ 0.0] (0): ( 8829 4414)
-> [0][2][ 72817] 0.0 [ 0.0] (0): ( 8027 2608)
-> [0][2][ 80907] 0.0 [ 0.0] (0): ( 7606 1514)
-> [0][2][ 89896] 0.0 [ 0.0] (0): ( 8161 1034)
-> [0][2][ 99884] 0.0 [ 0.0] (0): ( 7894 650)
-> [0][2][ 110982] 0.0 [ 0.0] (0): ( 8264 510)
-> [0][2][ 123313] 0.0 [ 0.0] (0): ( 7581 596)
-> [0][2][ 137014] 0.0 [ 0.0] (0): ( 7079 549)
-> [0][2][ 152237] 0.0 [ 0.0] (0): ( 7230 350)
-> [0][2][ 169152] 0.0 [ 0.0] (0): ( 7699 409)
-> [0][2][ 187946] 0.0 [ 0.0] (0): ( 5896 1106)
-> [0][2][ 208828] 0.0 [ 0.0] (0): ( 9608 2409)
-> [0][2][ 232031] 0.0 [ 0.0] (0): ( 12809 2805)
-> [0][2][ 257812] 0.0 [ 0.0] (0): ( 7996 3809)
-> [0][2][ 286457] 0.0 [ 0.0] (0): ( 18848 7330)
-> [0][2][ 318285] 0.0 [ 0.0] (0): ( 7747 9215)
-> [0][2][ 353650] 0.0 [ 0.0] (0): ( 11258 6363)
-> [0][2][ 392944] 0.0 [ 0.0] (0): ( 18775 6940)
-> [0][2][ 436604] 0.0 [ 0.0] (0): ( 12380 6667)
-> [0][2][ 485115] 0.0 [ 0.0] (0): ( 19986 7136)
-> [0][2][ 539016] 0.0 [ 0.0] (0): ( -6102 16612)
-> [0][2][ 598906] 0.0 [ 0.0] (0): ( 3783 13248)
-> [0][2][ 665451] 0.0 [ 0.0] (0): ( -3546 10288)
-> found max.
[0][2] working set size found: 485115, cost: 19986
migration: max_cache_size: 0, cpu: 2666 MHz:
migration_cost=39,3940
migration: 0 seconds
Dave
--
http://www.codemonkey.org.uk
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