-----Original Message----- From: u-boot-bounces@lists.denx.de [mailto:u-boot-bounces@lists.denx.de] On Behalf Of chris c Sent: Tuesday, October 12, 2010 6:55 AM To: u-boot@lists.denx.de Subject: Re: [U-Boot] Testing Data Cache for armv7 (beagleboard)
Thanks for the replies. I didn't realize that the MMC module was operating in 1-bit mode inside U-boot. I'll concentrate on looking at that. Has anybody done any work to try and get 4-bit mode working for OMAP3 in U-boot?
[Ghorai] can you give a test using this patch series? This uses the generic mmc/sd driver for beagle board. And mmc/sd card will work at 4-bit, 48Mhz. http://www.mail-archive.com/u-boot@lists.denx.de/msg38690.html
Thanks, Chris
On Thu, Oct 7, 2010 at 1:04 PM, Wolfgang Denk wd@denx.de wrote:
Dear chris c,
In message
<AANLkTi=usuEyf4YuUVWrrLu80bMRFpRF+BThEix2bFNg@mail.gmail.com<usuEyf4YuUVW rrLu80bMRFpRF%2BBThEix2bFNg@mail.gmail.com>>
you wrote:
I was comparing time just by timing it manually. How did you
instrument
u-boot to display the time?
That's no instrumentation of U-Boot, but just timestamping the output on the serial console. See for example ftp://ftp.denx.de/pub/tools/time_log
As for the small versus large file, I did the same test for 1MB of
data
using nand read and saw a x4 performance advantage. I also did a test
on
mmc with 100 MB file and saw no performance increase. Looks like file
size
doesn't matter.
So does that mean that MMC file loading will not benefit from dcache enabled? Can anybody explain this?
It depends on where the time is actually spent. If you have a slow (say, bit-banging) MMC driver and a low-performance CPU then the transfer from MMC might simply not depend as much on caches. It is wrong to check just a simple use case. Try a number of different operations, like umcompressing a large image in RAM or from NOR to RAM, or downloading over the net, or ...
Best regards,
Wolfgang Denk
-- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de "Remember, Information is not knowledge; Knowledge is not Wisdom; Wisdom is not truth; Truth is not beauty; Beauty is not love; Love is not music; Music is the best." - Frank Zappa