Write Speed On Sd With R121

[elfenkoenig]

I have a c-1000 and a 2gb sd with an ext2 and a swap partition.
Since i changed from beat3 to r121 i noticed that writing on sd is extremly slow and the the mmcqd prozess toke the whole cpu-power. Also when it began to use the swap, the system would be unuseable.
The sd-card has no bad blocks and works without problems in my desktop-pc.
Is it an configuration problem or could it be a driver bug?



sorry for bad english
thanks

[louigi600]

Adding SD support to the linux MMC driver is work in progress. There is work being done to speed it up but to my last readings it's in experimental phase.
While waiting for a better stable implementation try to see if things get better by avoiding to swap on the SD.

[elfenkoenig]

It is not only the swap, writing at all is nearly impossible (the last try copy 100mb on the sd i reseted it after one hour).
And i really need the sd space for installing programms and as swap.

Are there any other 2gb or 4gb sd-cards which are working on c-1000 with r121 without these problems?

Then i could buy me an other sd-card.

[Meanie]

It is not only the swap, writing at all is nearly impossible (the last try copy 100mb on the sd i reseted it after one hour).
And i really need the sd space for installing programms and as swap.

Are there any other 2gb or 4gb sd-cards which are working on c-1000 with r121 without these problems?

Then i could buy me an other sd-card.
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you could try using the async option instead of sync when mounting the SD. Thus would make it faster but you risk corrupting your files when you eject without properly unmounting the SD. With larger SD cards, ie > 1GB, you also risk corrupting your partition table/SD layout thingy and render your SD card unrecognizable...
use beta3 and be happy.

[louigi600]

I did a nand backup on a 1Gb SD and it took so long I hadto go off and do something elese ... on other cards it did not take so long so I guess a lot may depend on the card itself (the more expensive ones with the 40x label may work faster)

I've had corruption while using a 256Mb SD as root on beta4 ... not sure if things have gotten better in r121 ... but I now do my testing on a MMC card.
It's a bit more expensive but free from the SD intellectual property problems.
I recently got a 1Gb MMC for just 9 Euro more then the 1G SD (32, 23 respectively).
Can you try an MMC card (or at least a different SD) and see if it gets any better ?

[elfenkoenig]

Async helps only short time, then the same.
At home i have a 1gb sd which i could test in 2 or 3 weeks.
I really like r121, it feels much faster then beta3 and all other things, which i need, are working.

What about the speed between mmc and sd? I read that mmc are much slower then sd cards (if sd is working correctly).

[louigi600]

I had a a look at the performance of some SD with respect to my MMC.
They are different brands and different sizes ... here they are:
1Gb MMC (Transcend) 900 Kb/s
1Gb SD (Tossiba) 1.1 Mb/s
256 Mb SD (Kingston) 1.9 Mb/s
128 Mb SD (Panasonic) 700 Kb/s
I must add that all the devices (appart from the 256Mb Kingston) are really low price devices from which one can expect poor performance ... but what the hell my Z is'nt going to take off any way, save 50 to 75% off the hight priced device and be happy.

So my guess is that a lot depends on brand ... and that the brand can make an SD slower that an MMC.
I have no other MMC's to compare with but I'm sure that there will be a similar situation.

Incidently the onboard flash on my C760 performs at 1.4 Mb/s.

[Antikx]

louigi600, I added your SD card findings to the List.
Hope that's OK.

[Speedy]

@louigi600: Which program do you use for benchmarking?
I tested hardinfo but it crashes when opening the storage dialog.

Greetings from Germany
Andreas

---------
pdaxrom R121 | C1000

[louigi600]

@louigi600: Which program do you use for benchmarking?

I do it the old way (before there was explicit benchmark software)

I test read spead with:
time dd if=/dev/mmcblk0p1 of=/dev/null bs=1024 count=10240
I the calculate the avarage Mb per sek by division (10/real time)
This works on all linux distributions and flavors ;-)

write speed dangerous this way as it's distructive on data  and on format (but can be used on empty cards).
It is possible to write simple scripts that overwrite many times the same blocks but it's not healthy for flash devices.  
I use hdparm for write speed (although write speed is a minor concern as  I use the SD/MMC mainly for reading {multimedia files, maps, documents ... etc}).