On Mon, 2009-08-03 at 18:09 +0530, Vipin wrote: > Is this read or write speed? Can you isolate and find different > speed? Can you also check the read/write command code coming to the > driver? I remember of an issue where single block commands being sent > from MMC core resulting in low performance. > > Thanks and regards, > ~Vipin > > From: [email protected] > [mailto:[email protected]] On > Behalf Of zuowenping > Sent: Monday, August 03, 2009 5:02 PM > To: Steve Chen > Cc: davinci-linux-open-source > Subject: Re: Re: why is the sd/mmc so slowly in writing about dm355? > > thansk Steve Chen a lot! I am testing with a sd card(ScanDisk 1.0G)! >
IIRC single block command affects MMC but not SD. I did a few quick tests with a HP 2G SD card on the my DM355 EVM, and the console output are below. [email protected]:~# dd if=/dev/zero of=/mnt/disk/write-test1 bs=1M count=20 20+0 records in 20+0 records out 20971520 bytes (21 MB) copied, 1.07127 seconds, 19.6 MB/s [email protected]:~# [email protected]:~# dd if=/dev/zero of=/tmp/write-test2 bs=1M count=20 20+0 records in 20+0 records out 20971520 bytes (21 MB) copied, 0.531279 seconds, 39.5 MB/s [email protected]:~# [email protected]:~# dd if=/tmp/write-test2 of=/mnt/disk/write-test2 40960+0 records in 40960+0 records out 20971520 bytes (21 MB) copied, 8.96917 seconds, 2.3 MB/s [email protected]:~# dd if=/dev/zero of=/mnt/disk/write-test3 bs=1M count=100 100+0 records in 100+0 records out 104857600 bytes (105 MB) copied, 44.9918 seconds, 2.3 MB/s The first dd (write-test1) show unusually high data rate due to caching. dd returned before data is actually written to the SD card. I'm seeing about 2.3MB/s with an idle system on MV 2.6.18 kernel. The other MMC/SD slot has similar performance numbers. I'm not sure what caused the drastic difference in write performance between our systems. Regards, Steve _______________________________________________ Davinci-linux-open-source mailing list [email protected] http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
