Hello, I am doing some benchmarking on writes to the hdd from a simple application (attached). Im benchmarking the writes using the following - write with O_DIRECT - write with fadvise + O_SYNC - write with fadvise + sync_file_range
Ive tested the writes in chunks of 4/8/16 KB and 1MB The results show fadvise + sync_file_range is on par or better than O_DIRECT. Detailed results are attached. Now are these results along the expected lines? AFAIK O_DIRECT should be faster because it bypasses the cache. Does it make sense for apps to use fadvise + sync_file_range rather than use O_DIRECT? I havent tried benchmarking using tools like Iozone as yet. Hardware/OS details 1) AMD Athlon with 512 MB RAM running plain vanilla 2.6.20 (ext3 partition) 2) Intel P4 with 512 MB RAM running plain vanilla 2.6.20 (ext3 partition) Thanks Ameya
appl.tar.gz
Description: GNU Zip compressed data
O_DIRECT
4K 8K 16K 64K 1M
75626.34 53137.48 49263.58 48017.88 43199
44787 25452 17050 10442 8775
39895 97939 34024 18844 30244
111063 27507 27139 28850 44359
48343 29046 28858 82900 40925
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36919 28481 56743 37928 34170
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44939 32808 37180 37113 35865
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36842 28822 20563 37157 35801
40963 28863 136910 35663 35898
42155 28867 13272 28322 35811
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44020 28793 28858 37153 8286
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44965 28859 28862 64842 29335
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123426 27753 181516 20588 8686
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120922 106893 18759 11106 8464
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122677 114721 104940 152458 8400
123159 112336 20458 10075 85527
124142 113325 187358 12336 8480
124276 108468 104261 10157 85407
Fadvise + O_SYNC
4K 8K 16K 64K 1M
376290.86 202126.52 131960.98 76494.46 59176.52
330257 284465 100156 24233 19054
323958 193652 142911 74914 30224
357719 183639 149487 43475 90392
336065 166881 137875 114947 20033
340743 192979 89507 78008 117245
317783 181974 98894 98492 48205
351636 162300 109036 19969 51045
347116 170515 107965 81623 89149
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339150 148410 107109 31272 12311
338398 168031 109812 102671 85124
329884 172748 121741 29860 12899
342271 150067 133982 94922 84807
330628 183596 123372 62554 12467
558715 156611 89231 121640 93566
365960 173794 103880 66925 12245
353970 157820 131674 76353 87231
376809 156348 97552 41378 12704
349713 169535 111219 117543 85127
389939 162914 121444 48571 12266
366682 166365 110327 70402 85495
329085 176377 136800 80525 12314
322519 160928 117013 79167 76546
371126 170565 124932 65822 12200
340151 165020 116263 29476 84982
369965 165502 121148 156296 12822
363818 178192 114615 73100 85061
358747 163731 110885 62335 12211
320117 167126 133125 42280 85532
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435780 233689 184194 132836 14198
Fadvise
4K 8K 16K 64K 1M
68731.44 54785.04 43424.16 50675.74 53662.22
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44940 28860 29225 73881 42943
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44601 29347 14753 111475 70690
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39065 36044 28854 28861 26130
43345 29162 27136 100312 70684
45889 28555 28857 11279 11676
45584 28862 28865 14421 24567
47868 28861 20303 80027 66358
43100 28860 17709 22290 11953
39529 24043 61646 63433 27332
46386 40337 56458 11468 69087
46438 28826 14683 16734 11696
37284 28835 15559 26140 42117
47199 28851 30653 105319 31073
46785 27219 116569 25272 91205
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45141 28877 69241 43902 37290
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