Hi David,

On 6/19/19 3:38 AM, David Christensen wrote:

The best way to answer your question regarding performance of a size N SD card vs. a size 2*N SD card is to buy two cards and benchmark them using your workload.  Please publish your findings.

Please find my four (4) findings below or at http://paste.debian.net/1088723

The only benchmark I know how to use is flashbench. But unfortunately I don't know how to interpret the resulting data.

I would be immensely grateful for advise on which of the 4 cards to use.

The testing was simple. I have downloaded and put the same copy of the redpill RC3 image from http://box.redpill.dk/nonfree/ onto each SD card, then I have followed the instructions. Each card now has an "Extended system" created by the command box-add-gui on the same machine.

Then I have installed aptitude, run update and upgrade and autoclean, and then installed and run flashbench with parameters: flashbench -a /dev/mmcblk0 --blocksize=1024

The four cards are:

MicroSD SanDisk Extreme PRO  64GB  [3]  XC II
MicroSD SanDisk Extreme PLUS  64GB  [3]  XC I  V30  A2
MicroSD SanDisk Extreme PLUS  32GB  [3]  HC I  V30  A1
MicroSD SanDisk Ultra  32GB  [1]  HC I  (10)  A1

I can send a picture of the cards off list if this is unclear.

So the question is, which card should I use for Teres-I ?

If there are further benchmarks or tests that could help determine which SD card is the best, I'd be happy to run them.

Best regards.

//Erik

MicroSD SanDisk Extreme PRO  64GB  [3]  XC II
debian@box:~$ sudo flashbench -a /dev/mmcblk0 --blocksize=1024
align 17179869184       pre 515µs       on 809µs        post 452µs      diff 
325µs
align 8589934592        pre 515µs       on 736µs        post 427µs      diff 
265µs
align 4294967296        pre 537µs       on 823µs        post 460µs      diff 
325µs
align 2147483648        pre 545µs       on 893µs        post 471µs      diff 
385µs
align 1073741824        pre 517µs       on 749µs        post 434µs      diff 
274µs
align 536870912 pre 526µs       on 763µs        post 445µs      diff 277µs
align 268435456 pre 527µs       on 769µs        post 448µs      diff 282µs
align 134217728 pre 540µs       on 820µs        post 446µs      diff 327µs
align 67108864  pre 514µs       on 754µs        post 449µs      diff 273µs
align 33554432  pre 506µs       on 722µs        post 417µs      diff 261µs
align 16777216  pre 539µs       on 660µs        post 460µs      diff 160µs
align 8388608   pre 539µs       on 670µs        post 458µs      diff 171µs
align 4194304   pre 541µs       on 669µs        post 466µs      diff 165µs
align 2097152   pre 547µs       on 649µs        post 463µs      diff 144µs
align 1048576   pre 544µs       on 639µs        post 458µs      diff 138µs
align 524288    pre 545µs       on 658µs        post 460µs      diff 155µs
align 262144    pre 545µs       on 655µs        post 460µs      diff 152µs
align 131072    pre 540µs       on 620µs        post 455µs      diff 122µs
align 65536     pre 541µs       on 624µs        post 458µs      diff 125µs
align 32768     pre 538µs       on 622µs        post 461µs      diff 122µs
align 16384     pre 478µs       on 633µs        post 457µs      diff 165µs
align 8192      pre 501µs       on 516µs        post 480µs      diff 25.7µs
align 4096      pre 509µs       on 528µs        post 465µs      diff 41.2µs
align 2048      pre 514µs       on 538µs        post 508µs      diff 27.6µs


MicroSD SanDisk Extreme PLUS  64GB  [3]  XC I  V30  A2
debian@box:~$ sudo flashbench -a /dev/mmcblk0 --blocksize=1024
align 17179869184       pre 567µs       on 603µs        post 494µs      diff 
72.6µs
align 8589934592        pre 557µs       on 583µs        post 442µs      diff 
83.9µs
align 4294967296        pre 689µs       on 784µs        post 564µs      diff 
157µs
align 2147483648        pre 654µs       on 726µs        post 593µs      diff 
103µs
align 1073741824        pre 579µs       on 638µs        post 522µs      diff 
87.7µs
align 536870912 pre 570µs       on 652µs        post 529µs      diff 102µs
align 268435456 pre 524µs       on 564µs        post 500µs      diff 52.5µs
align 134217728 pre 654µs       on 730µs        post 616µs      diff 95.3µs
align 67108864  pre 664µs       on 728µs        post 600µs      diff 96.3µs
align 33554432  pre 576µs       on 637µs        post 530µs      diff 84.1µs
align 16777216  pre 628µs       on 694µs        post 568µs      diff 95.9µs
align 8388608   pre 594µs       on 654µs        post 567µs      diff 73.6µs
align 4194304   pre 628µs       on 680µs        post 580µs      diff 76µs
align 2097152   pre 576µs       on 602µs        post 562µs      diff 33.5µs
align 1048576   pre 578µs       on 577µs        post 572µs      diff 2.21µs
align 524288    pre 585µs       on 585µs        post 578µs      diff 3.55µs
align 262144    pre 587µs       on 592µs        post 584µs      diff 6.52µs
align 131072    pre 616µs       on 636µs        post 613µs      diff 21.4µs
align 65536     pre 594µs       on 586µs        post 596µs      diff -8963ns
align 32768     pre 636µs       on 695µs        post 587µs      diff 83.6µs
align 16384     pre 548µs       on 551µs        post 550µs      diff 2.51µs
align 8192      pre 551µs       on 555µs        post 546µs      diff 6.74µs
align 4096      pre 579µs       on 604µs        post 547µs      diff 40.7µs
align 2048      pre 586µs       on 579µs        post 586µs      diff -6480ns

MicroSD SanDisk Extreme PLUS  32GB  [3]  HC I  V30  A1
debian@box:~$ sudo flashbench -a /dev/mmcblk0 --blocksize=1024
align 8589934592        pre 329µs       on 367µs        post 302µs      diff 
51.3µs
align 4294967296        pre 360µs       on 407µs        post 304µs      diff 
74.6µs
align 2147483648        pre 344µs       on 370µs        post 322µs      diff 
36.8µs
align 1073741824        pre 408µs       on 455µs        post 409µs      diff 
46.5µs
align 536870912 pre 436µs       on 486µs        post 411µs      diff 62.6µs
align 268435456 pre 428µs       on 449µs        post 402µs      diff 34.2µs
align 134217728 pre 417µs       on 452µs        post 392µs      diff 47.7µs
align 67108864  pre 433µs       on 481µs        post 414µs      diff 57.6µs
align 33554432  pre 307µs       on 345µs        post 318µs      diff 32µs
align 16777216  pre 359µs       on 381µs        post 303µs      diff 50.5µs
align 8388608   pre 360µs       on 398µs        post 316µs      diff 59.8µs
align 4194304   pre 352µs       on 391µs        post 300µs      diff 64.8µs
align 2097152   pre 316µs       on 315µs        post 317µs      diff -1358ns
align 1048576   pre 322µs       on 323µs        post 320µs      diff 1.96µs
align 524288    pre 325µs       on 334µs        post 325µs      diff 9.38µs
align 262144    pre 326µs       on 327µs        post 326µs      diff 443ns
align 131072    pre 328µs       on 343µs        post 325µs      diff 16.1µs
align 65536     pre 307µs       on 306µs        post 306µs      diff -688ns
align 32768     pre 315µs       on 314µs        post 316µs      diff -1308ns
align 16384     pre 328µs       on 331µs        post 326µs      diff 3.87µs
align 8192      pre 306µs       on 304µs        post 308µs      diff -2568ns
align 4096      pre 303µs       on 324µs        post 307µs      diff 19.5µs
align 2048      pre 309µs       on 309µs        post 311µs      diff -1260ns

MicroSD SanDisk Ultra  32GB  [1]  HC I  (10)  A1
debian@box:~$ sudo flashbench -a /dev/mmcblk0 --blocksize=1024
align 8589934592        pre 351µs       on 380µs        post 317µs      diff 
46.3µs
align 4294967296        pre 368µs       on 399µs        post 316µs      diff 
57.4µs
align 2147483648        pre 358µs       on 383µs        post 347µs      diff 
30µs
align 1073741824        pre 409µs       on 454µs        post 403µs      diff 
47.9µs
align 536870912 pre 360µs       on 395µs        post 360µs      diff 35.2µs
align 268435456 pre 408µs       on 447µs        post 378µs      diff 53.6µs
align 134217728 pre 366µs       on 391µs        post 358µs      diff 28.5µs
align 67108864  pre 474µs       on 512µs        post 451µs      diff 49.3µs
align 33554432  pre 344µs       on 370µs        post 338µs      diff 28.6µs
align 16777216  pre 383µs       on 410µs        post 342µs      diff 47.3µs
align 8388608   pre 378µs       on 407µs        post 339µs      diff 48.5µs
align 4194304   pre 380µs       on 401µs        post 349µs      diff 36.8µs
align 2097152   pre 367µs       on 368µs        post 356µs      diff 6.37µs
align 1048576   pre 375µs       on 374µs        post 362µs      diff 5.4µs
align 524288    pre 380µs       on 393µs        post 365µs      diff 20.6µs
align 262144    pre 379µs       on 380µs        post 369µs      diff 6.17µs
align 131072    pre 382µs       on 382µs        post 371µs      diff 5.39µs
align 65536     pre 382µs       on 380µs        post 371µs      diff 3.25µs
align 32768     pre 384µs       on 383µs        post 369µs      diff 6.38µs
align 16384     pre 375µs       on 374µs        post 373µs      diff 387ns
align 8192      pre 372µs       on 374µs        post 374µs      diff 456ns
align 4096      pre 379µs       on 391µs        post 375µs      diff 14.3µs
align 2048      pre 382µs       on 383µs        post 379µs      diff 2.12µs

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