(04-30-2016, 10:36 PM)NondescriptMember Wrote: For example. would I get the same results on the same card in a different computer?
Depends. For example: I've a few rather expensive SanDisk Extreme Pro (if you buy SanDisk either buy Pro or Plus, the 'normal' SanDisks show very low random I/O write performance especially at 16K sector size).
When I write OS images to them on my MacBook I get sequential write speeds of up to 80 MB/s (which is nice since burning images is fast). But if I use the card in Pine64 then sequential transfer speeds are limited to the Pine64's SDIO implementation (4 bit @ 50 MHz --> theoretical limit of 25MB/s, in reality it's 22-23 MB/s and sequential writes are a little bit slower than reads).
SEQUENTIAL transfer speeds are close to IRRELEVANT when we talk about SBC useage. So it's both useless to look after any product that is advertised with 'more than 25 MB/s' and sequential transfer speeds don't matter at all.
Get a fresh card that shows superiour random I/O performance and don't buy no-name crap (Kingston, PNY and the like -- they all buy cheap NAND dies and controllers on the spot markets and all you get are slow cards that just fulfil the irrelevant sequential speed class ratings)
(04-30-2016, 10:36 PM)NondescriptMember Wrote: I realize that the point is to source a micro SD card with as fast a random I/O as possible, but how do we know what's fastest to the Pine64+ ?
All these results collected here apply to Pine64: http://forum.armbian.com/index.php/topic...rformance/
Random I/O performance depends not that much on the host's SDIO or USB implementation but on the controller used inside the SD card. So while sequential speeds differ between different hosts, random I/O performance varies only a little bit.
(04-30-2016, 08:02 PM)NondescriptMember Wrote: I now know that my issues are with my card. Here are my results:
Yes, very slow random I/O performance: very sluggish Android/RemixOS behaviour. Everything as expected.
The eMMC used in typical Android devices is magnitudes faster than the PNY card you use (even if sequential transfer speeds might look slower -- only random I/O matters)