SDHC kernel updated - mk3
 

http://intr.overt.org/blog/?p=49

2.2006.51-6 kernel updated with the latest SDHC/MMC patches, fixing low-voltage MMC and high-speed MMC issues.

Re: SDHC kernel updated - mk3
 

Anyone with Transcend 150x 4GB (non-SDHC one) could post clock debug log from this SDHC kernel and also test the speed like this (two times, post the second/slower one)?

I've got older 80x transcend 1GB which does run in high-speed SD mode (i.e. 48MHz) but still the read speed is ~7MB/s. I wonder whether the 150x one could be better (it should).

The kingston 2GB mmcmobile is my best card so far, it runs at 48Mhz over 4bits and read speed in N800 is 12MB/s, which is great. Can the 4GB 150x one match or exceed this?

240MB in 19 seconds =~ 12.5 MB/s

Re: SDHC kernel updated - mk3
 

Fanoush - I've got similar results when comparing high-speed and low-speed cards, though I'm not sure why there is such a difference between the 8GB and 4GB Transcend cards, they're seemingly identical other than capacity however the higher capacity card is significantly faster on reads.

Re: SDHC kernel updated - mk3
 

I flashed my n800 with this kernel.bin last night and lo my 8gb Transcend sdhc card works! :)

Now I'm at work listening to some of the many MP3's I've now got on the card in Canola. Occasionally there's a glitch (slight pause) early on in a track, if I restart the track I don't get the glitch, so its not in the file itself (happens on several different tracks too). I also never had this happen with my other 2gb stard sd card.

I'm just wondering what could be causing this, the README on Philip's webpage (dir with the bin file) mentions something about a debug file being written, could this be happening?

I'm not fully up to speed with linux yet, so I'm struggling to find said debug file, otherwise I could just check the time/date on it.

Any advice would be appreciated.

Re: SDHC kernel updated - mk3
 

I don't know how to get the debug logs.
Here is the timing for my two cards mmcblk0 being the Transcend 150x 2gig (internal) and mmcblk1 being a not even specced (none included in blister pack) Kingston 2gig. I tested before installing the sdhc kernel and the mmcblk0 was 32 secs and the kingston 34 secs, didn't screen cap it :/

the results below are unexpected, I expected the transcend to be in line with the other results here, the kingston I expected nothing from and I got a roughly 1/3 gain.
Cliff

Nokia-N800-51:~# time dd if=/dev/mmcblk0 of=/dev/null bs=8192 count=30000
30000+0 records in
30000+0 records out
real 0m 20.91s
user 0m 0.03s
sys 0m 3.69s
Nokia-N800-51:~# time dd if=/dev/mmcblk0 of=/dev/null bs=8192 count=30000
30000+0 records in
30000+0 records out
real 0m 20.93s
user 0m 0.04s
sys 0m 3.78s
Nokia-N800-51:~# time dd if=/dev/mmcblk1 of=/dev/null bs=8192 count=30000
30000+0 records in
30000+0 records out
real 0m 21.59s
user 0m 0.07s
sys 0m 3.88s

Re: SDHC kernel updated - mk3
 

kernel log is recorded to kernel buffer in RAM so it should not slow down anything. This one adds just few lines about MMC clock speed when card is inserted. You can print it via dmesg command typed in osso-xterm. As the buffer is circular and limited by size you see only last messages.

Thanks CliffOn for your numbers, looks like the 150x one is good choice (speedwise).

Re: SDHC kernel updated - mk3
 

I'll try the previous SDHC kernel, maybe the latest is too optimised for speed for my card?

Re: SDHC kernel updated - mk3
 

I'm experienceing the same glitches with my 8gb Transcend while listening to my mp3s.
I'm still using the first SDHC kernel.

Anyone else?

Re: SDHC kernel updated - mk3
 

Just realised these glitches only happen in Canola, so I can live with using the nokia media player, still pretty happy with having a 10gb media player / internet browser!

Rok, do you have the same results with media player?

Re: SDHC kernel updated - mk3
 

Test Results for 2 cards: OCZ 1 GB 133X and ATP ProMAX 4GB SDHC Class 6

Card placement: the ATP is in the Internal Bay, OCZ is in the external slot.

Results:
Is there any way we can test write speeds using something similar to this method? That Kingston looks pretty good, considering that this ATP is not exactly cheap.

Re: SDHC kernel updated - mk3
 

According to your figures the ATP Class 6 (in the internal mmcblk0 slot) is about 10% faster than the OCZ in the external/mmcblk1 slot, and both cards are about the same speed as my Class 2 8GB Transcend (~19.5s).

The only thing I can deduce from these figures is that the read performance is not affected in any way by the "Class" of the card and a Class 2 card will transfer (read) data as quickly as a Class 4 or Class 6 card, assuming all other variables are the same (high-speed and wide bus both enabled). Also, based on your figures a "fast" SD card is unlikely to be faster than a standard SDHC Class 2 card (your OCZ is slower than my Transcend).

As for testing "write" performance - this is tricky as the OS will buffer writes giving unrealistic performance figures. Hopefully someone else can suggest a methodology to test write performance.

Until we can get firm figures on write performance, if anyone is looking to buy extra storage my advice would be to buy Class 2 SDHC cards, avoid SanDisk (no high-speed support) and don't spend too much as you're unlikely to see any real benefit for the extra outlay. :)

I've had a good experience with Transcend - reasonably cheap 4GB and 8GB Class 2 capacities (in the UK £25 and £50 respectively), and they have high-speed and wide bus support.

:)

Re: SDHC kernel updated - mk3
 

I've just run this speed test on a couple of cards I've bought for my n800:

The Integral card was listed as ORA on the website (expansys.com) but it's branded Integral on the card itself.

Integral 4gb sdhc run #1 - ext slot:
real 0m 18.14s
user 0m 0.08s
system 0m 3.21s

Integral 4gb sdhc run #2 - ext slot
real 0m 19.63s
user 0m 0.13s
sys 0m 3.25s

Inov8 1gb "3-in-1" sd run #1 - int slot
real 0m 26.49s
user 0m 0.14s
sys 0m 2.94s

Inov8 1gb "3-in-1" sd run #2 - int slot
real 0m 26.20s
user 0m 0.09s
sys 0m 3.35s

Re: SDHC kernel updated - mk3
 

From what I understand about the new class ratings: yes, they are referring to the minimum write speeds. All previous SD cards, where they advertise 120X or 150 X were usually referring to reading speeds. I read somewhere that the SD Association mandated that the new format have a minimum write speed - hence the different classes.

I've found a few reviews online which suggest that Sandisk SDHC cards are horrible in terms of price / write performance.

http://www.extremetech.com/article2/...2094734,00.asp

http://techgage.com/article/sd_card_roundup/

None of these reviews that I've listed use an exact scientific approach to benchmarking, but it is interesting reading. The price I paid for the ATP was almost enough for an 8gb Transcend. I would have bought that, but I was unsure about the quality and the read/write speeds. I would guess that the Kingston Class 2 would be a good all rounder and the Transcend a good value buy.

EDIT: Forgot to mention that anybody planning on running the tests should DISABLE virtual memory - I've found that it'll add a couple seconds to results. Test results seem to fluctuate a lot too.

Re: SDHC kernel updated - mk3
 

Yes, me too. It is worse when booting from the card. Any write to card causes audio to skip. It is caused by raised priority of mmcqd kernel daemon. I'm not sure if it is intentional or bug. With Nokia kernel mmcqd has normal priority (=0) with sdhc patches it is raised to -5. It can be fixed by running as root after each boot. I notified Philip Langdale about it.

Re: SDHC kernel updated - mk3
 

Thanks for searching!
Seems to work.
:-)

Re: SDHC kernel updated - mk3
 

To test write speed I use something like that:

$ sync; time sh -c "dd if=/dev/zero of=testw1 bs=1M count=100;sync"

dd will output a useless MB/s, but time "real" output is what you're looking for, 100/"real time" will give you MByte/second.

Hope this helps,

Laurent