Re: USB and SD performance issue

[Koen Kooi]

Op 3 feb 2009, om 12:16 heeft Remith Ravi het volgende geschreven:

Hello,

Recently I have done a performance comparison of OMAP3 'USB OTG Host'
and 'SD' drivers on different Linux Kernels.


The performance is calculated by doing data transfer between RAM and
the storage device (using 'time' command).

The performance details are given below.

1) 2.6.29-rc2 kernel
USB OTG (Host)         Read (4.2 MB/s)          Write (2.6 MB/s)        
SD Card                     Read (3.88 MB/s)            Write (3.1 MB/s)

2) 2.6.28 kernel
USB OTG (Host)         error                            error   
SD Card                     Read  (4.2 MB/s)            Write (3.27 MB/s)

3) 2.6.22 TI kernel
USB OTG (Host)         Read (5.4MB/s)           Write (6.14MB/s)        
SD Card                      Read (6.7MB/s)             Write (6.43MB/s)

The performance of latest git kernel is less comparing to 2.6.22 TI kernel. Could some one please explain me what cause this performance difference?

I get this with 2.6.28:

r...@omap3evm:~# hdparm -t /dev/mmcblk0
/dev/mmcblk0:
 Timing buffered disk reads:   42 MB in  3.10 seconds =  13.53 MB/sec

r...@beagleboard:~# hdparm -t /dev/mmcblk0
/dev/mmcblk0:
 Timing buffered disk reads:   44 MB in  3.13 seconds =  14.04 MB/sec

regards,

Koen

Regards,
Remith
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