Flash I/o Performance Database?

[uth]

Is there a comprehensive database on the net that compares the read/write speed of various CF/SD cards?   I have several cards, and I want to figure out which is the fastest so I can install the apps that would benefit most from the speed on them.

[ChrisZ]

Have a look at http://www.robgalbraith.com/bins/multi_pag...p?cid=6007-6133

But don't expect too much. According to speed tests posted in the forum and my own tests, the Zauri can't transfer data faster than about 3000 kB/s even with fast SanDisk Ultra II-cards. Don't buy a too expensive card.

If you're interested: I accumulated the speed infos I had found into a text file. And: I've just ordered a SanDisk 4 GB Standard (Zaurus) und a 4 GB Extreme III (camera) card. I will perform a speed test with these cards, too.

[uth]

Have a look at http://www.robgalbraith.com/bins/multi_pag...p?cid=6007-6133

But don't expect too much. According to speed tests posted in the forum and my own tests, the Zauri can't transfer data faster than about 3000 kB/s even with fast SanDisk Ultra II-cards. Don't bye a too expensive card.

If you're interested: I accumulated the speed infos I had found into a text file. And: I've just ordered a SanDisk 4 GB Standard (Zaurus) und a 4 GB Extreme III (camera) card. I will perform a speed test with these cards, too.
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Good to know about the 3000 Kb/s limit.   Is either of the SD or CF port faster than the other, or are they about the same?

[ChrisZ]

The SD slot is max 1700 kB/s. Perhaps the new Sharp SD driver performs better.

[uth]

The SD slot is max 1700 kB/s. Perhaps the new Sharp SD driver performs better.
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Interesting.  Isn't that roughly the speed of the USB port too?

[Da_Blitz]

there are major limitations with the CF slot on the intel Xscales, mainly they share the bus betwwen the 2 CF cards (on the cxx00 series) the flash and memory, so you get a copy from CF then a copy to memory then a copy to the second card, teseting on others is the same but you end up with a copy to flash instead of to CF at the end, the flash bieng the slowest

USB should be 12Mbit * 80% max or 9.6Mbit or 1200KByte/s (Bulk class transfers are not more than 80% of system bandwidth)

CF max speed on an intel Xscale is 16MB IF you only acsess the CF card and not anything else, eg memory (you basically have to run from cache

SD is a bit better, it tops out at a max of 25MB/s however at the moment as far as i can tell (not sure about a 2.6 kernel) the cards are booted as mmc cards so you dont get the full speed

the advantage in SD and USB is the dont hog the MEM bus so you can recive data and read memory at the same time

[ChrisZ]

there are major limitations with the CF slot on the intel Xscales, mainly they share the bus betwwen the 2 CF cards (on the cxx00 series) the flash and memory, so you get a copy from CF then a copy to memory then a copy to the second card, teseting on others is the same but you end up with a copy to flash instead of to CF at the end, the flash bieng the slowest

USB should be 12Mbit * 80% max or 9.6Mbit or 1200KByte/s (Bulk class transfers are not more than 80% of system bandwidth)

CF max speed on an intel Xscale is 16MB IF you only acsess the CF card and not anything else, eg memory (you basically have to run from cache

SD is a bit better, it tops out at a max of 25MB/s however at the moment as far as i can tell (not sure about a 2.6 kernel) the cards are booted as mmc cards so you dont get the full speed

the advantage in SD and USB is the dont hog the MEM bus so you can recive data and read memory at the same time
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That may be right. But I tested the transfer speed from CF internal (instead of the MD) to CF external with 2 SanDisk Ultra II in both directions: ~950-1050 kB/s. And CF internal/extrenal to SD (Kingston MMC plus): ~750 kB/s. The native speed CF/SD to /dev/null was 2500/1600 kB/s.

The mem bus-hog doesn't seem to be so important (in this special case).

[Da_Blitz]

What i really ment is with the bus issues you can only achive a max of 16MB/3 (5.3MB/s) max in theroy

your right, the mem bus thing is not important at the momont but it is if you watch a moive, it has been noted that betaplayer benghmarks were lower when played back from a CF card due to the high amount of bus usage and conflicts

it was worse with a wifi card

try it out by playing a moive frem the CF and SD or USB devices with mplayer -benchmark -nosound, i havent tried this but am intrested in the resaults, my bet is that CF would lead the pack but you wauld see a larger performance hit for higher bitrate moives than the other 2 (also you might want to update your SD drivers to get more speed and look at the resaults before and after)

[ChrisZ]

Hmmm. The results were the following:

Video: divx5, 640x480, avi, 12.5 fps, 350 kbit/s
Audio: mp3, 64 kbit/s, mono, 48 kHz
Length: ~143 s, ~7.2 MB
Kernel: Tetsu 18a for C3000
Mplayer opts: -benchmark -nosound

Played from CF (SanDisk Ultra 1 GB)
91.888 s

Played from SD (Kingston MMC Plus 256 MB)
91.614 s

I would say, the results are exactly the same. The most important thing is the decoding of the video. Remember: The transfer of the 7 MB video takes 2-3 s from CF/SD to memory. That's nothing compared to the 90 s overall time.

Without the -nosound option the time is 144s for 143s video. This means that the Z cannot handle more video data than included in my test file.

After all I would say: It doesn't make a difference what kind of card you use for video playing.

[speculatrix]

so really, as long as you don't have an old slow card, the only advantage in getting a fast card is that if you can copy content onto it faster when using a PC with USB2 card reader.

[Da_Blitz]

Yeah, most of the stuff i am talking about is fairly thereticol but i would say speculatrix is right and that i wauld be inclined to watch moives off the SD card for power reasons (coompared to the microdrive)

btw you should try benchmarking with the betaplayer benchmark files (epessially the 640 wide 16:9 @ 1.5Mbps Xvid file, it brings most PDA's to thier knees and in my opinion is the best file to benchmark with)

one other peice of infomation thats burried on the sandisk website is an app note that talks about how they get that top speed, normally its DMA transfers an a dedicated bus while setting the microdrive up for the largest transfer possible, plus they make sure never to exceed the buffer size so that all you really get is the buffer speed