o/~ Talking to myself in public o/~

On Sun, 23 Feb 2020 10:19:08 -0500, Dennis Lee Bieber
 declaimed the following:

> An R-Pi specific page -- which includes instructions for duplicating
>the benchmarks: https://www.pidramble.com/wiki/benchmarks/microsd-cards
>"""
>Most cheap microSD cards, even if rated as being 100MB/sec+ class 10 cards,
>can’t sustain anywhere near that rate when writing random data—especially
>on the Raspberry Pi’s measly data bus. (Note that most of the above
>benchmarks, when run on a USB 3.0 card reader on my MacBook Air, show 5,
>10, or 15 times greater performance in that environment).
>"""
>
>{Hmmm, wonder if that benchmark will also run on the BeagleBones}

BeagleBone Black
SanDisk Edge 8GB Class 4 HC I8227DTJLT009
(no clock speed line)
 Timing buffered disk reads:  66 MB in  3.06 seconds =  21.54 MB/sec
                                                              random random
              kB  reclen    write  rewrite    read    reread    read write
          102400       4     2288      195     6249     6246     5289 1211


Raspberry-Pi 3B+
Kingston 16GB Class 10 HC I U1 SDC10G2/16GB N0581-002.A00LF
microSD clock: 50.000 MHz
 Timing buffered disk reads:  66 MB in  3.03 seconds =  21.81 MB/sec
                                                              random random
              kB  reclen    write  rewrite    read    reread    read write
          102400       4      242      233     5875     5852     5183 234

 From iozone listing the "Output is in kBytes/sec"... I don't have the
"dd" test results (hadn't realized it wrote to screen, not the redirected
output file).

 Lets make that easier to compare by running it as columns (and for
giggles, the BBB 4GB eMMC). I'm going to rerun (to get "dd" results, and
copy the numbers from PuTTY session -- so they may differ some from the
above cut&paste; especially as I've run apt update/upgrade just before the
reruns).

metric BBB   RPi3B+  eMMC
bdr-MB 21.74  21.97  hdparm did not run (tried to access SD)
dd-sec 89.4367 67.4917 63.8932
dd-MB 4.7   6.2   6.6 
write 1652  250   1814
rewrite 2306*  237   1888
read 6371  5814  5039
reread 6375  5798  5038
ranread 5364  5138  3562
ranwrite 1157  234   395

* Hmmm, the "rewrite" test came out 10X the speed of the first time
(shown above) that I ran it. Documentation for iozone does state that
rewrite is expected to be faster than write, so this may be a correct
value.


 On the SD cards, the hdparm "buffered disk read" speed is practically
the same. I didn't try modifying the script to properly access the eMMC.

 The "dd" output shows the SanDisk Class-4 is slower than the Kingston
Class-10 and the eMMC -- by about a third.

 The iozone output is telling, however. I started the BBB SD card rerun
5 minutes after the R-Pi3B+ and the latter is still running 10 minutes
after the BBB finished!

***********************************************************************
***********************************************************************
***********************************************************************
 That Class-10 Kingston card lost to the Class-4 SanDisk on ALL iozone
tests -- the C4 card is 5 to 10 times faster on write, rewrite, and random
write tests, and 10% faster on read operations. Even the onboard 4GB eMMC
of the BBB was faster on write operations.
***********************************************************************
***********************************************************************
***********************************************************************

 For writing streaming data (~"dd") to a single file, the Kingston and
eMMC are a close match, and faster than the SanDisk. But overall -- that
Class-4 SanDisk is a much better match to operations on a journaling file
system such as Linux EXT3/4. When writing to multiple small files (such as
logs) the Kingston STINKS. I should write the Pi-Star software to that card
and put it into my radio hotspot -- since Pi-Star normally runs as a R/O
file-system, putting logs into a RAM disk.



--
 Wulfraed                 Dennis Lee Bieber         AF6VN
 wlfraed@ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/

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