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Re: Only 2,9Mb/s on SD-Card from /dev/zero ??

Karl Krach
Intellectual 320 points

Marc,

I ve switched to the original TI kernel and rootfs and repeated my tests - still the same results. I used the default mount options, since when mounting with sync it takes even for 1Mb about 20 seconds.

In the datasheed you ve written, that you have disabled the CPU power management. Is it enabled in the default configuration - if yes, how can I disable it? Further more you use a ext2 filesystem - could this make the difference?

root@c6a816x-evm:~# sync; time dd if=/dev/zero of=output.dat count=200000; echo; time sync
   200000+0 records in
   200000+0 records out
   real    0m 29.62s
   user    0m 0.00s
   sys     0m 0.00s

   real    0m 5.84s
   user    0m 0.00s
   sys     0m 0.00s
root@c6a816x-evm:~# mount -oremount,sync /
root@c6a816x-evm:~# mount | grep "root\|mmc"
rootfs on / type rootfs (rw)
   /dev/root on / type ext3 (rw,sync,relatime,errors=continue,data=writeback)
   /dev/mmcblk0p2 on /media/mmcblk0p2 type ext3 (rw,sync,relatime,errors=continue,data=writeback)
   /dev/mmcblk0p3 on /media/mmcblk0p3 type ext3 (rw,relatime,errors=continue,data=writeback)
   /dev/mmcblk0p1 on /media/mmcblk0p1 type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
root@c6a816x-evm:~# sync; time dd if=/dev/zero of=output.dat count=2000; echo; time sync 
   2000+0 records in
   2000+0 records out
   real    0m 17.13s
   user    0m 0.00s
   sys     0m 0.00s

   real    0m 1.45s
   user    0m 0.00s
   sys     0m 0.00s
root@c6a816x-evm:~# ls -lah | grep output
   -rw-r--r--    1 root     root      1000.0K Nov 19 10:44 output.dat
root@c6a816x-evm:~#

Best regards,

Charly

  • 0
    Intellectual 320 points

    The measurements above I ve used a "SanDisk Extreme 30MB/s 8Gb" with a custom compiled kernel from the ARGO git repository (linux-2.6.34-psp04.00.00.07). I ve repeated the tests with the original SD-Card from the EMV, which is labeled with

    8GB SD
    C6A816A/AM389x
    Demos and SDK
    Linux Kernel
    2.6.34 Demo
    513844-0001A

    The results from this are:

    root@c6a816x-evm:~# mount | grep root
    rootfs on / type rootfs (rw)
    /dev/root on / type ext3 (rw,relatime,errors=continue,data=writeback)
    root@c6a816x-evm:~# rm output.dat ; sync; time dd if=/dev/zero of=output.dat cou
    nt=200 bs=1M; echo; time sync
    200+0 records in
    200+0 records out
    real    1m 19.74s
    user    0m 0.00s
    sys     0m 0.00s

    real    0m 6.21s
    user    0m 0.00s
    sys     0m 0.00s
    root@c6a816x-evm:~# uname -a
    Linux c6a816x-evm 2.6.34 #1 Thu Nov 18 22:18:53 IST 2010 armv7l unknown
    root@c6a816x-evm:~#

    Regards

    Charly

  • 0
    TI__Expert 8250 points

    Karl

    I was able to re-run the tests with the latest code and i observed that the performance with ext3 is almost of half of what we can achieve with vfat. The number for vfat are close 6MB/sec and with ext3 the number is down to almost 3MB/sec. I am sure the results with your working code base are going to be similar.

    we do feel that the numbers with ext2 should be better than that of ext3. At this point improving the MMC/SD performance from 6MB/sec will need closer inspection and analysis. Until we get that resolved can you consider moving to vfat /ext2  in the interim

     

    Logs attached:

    ------------------------------------------With vfat --------------------------------

    root@ti8168-evm:/media/mmcblk0p1# sync ; time dd if=/dev/zero of=output.dat coun

    t=200 bs=1M ;echo ; time sync

    200+0 records in

    200+0 records out

    real    0m 30.21s

    user    0m 0.00s

    sys     0m 1.77s

     

    real    0m 2.59s

    user    0m 0.00s

    sys     0m 0.02s

    root@ti8168-evm:/media/mmcblk0p1# mount

    rootfs on / type rootfs (rw)

    172.24.179.98:/groups/psp/anil/netra/nfs_root on / type nfs (rw,relatime,vers=3,rsize=262144,wsize=262144,namlen=255,hard,nolock,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=172.24.179.98,mountvers=3,mountproto=tcp,local_lock=all,addr=172.24.179.98)

    devtmpfs on /dev type devtmpfs (rw,relatime,size=62380k,nr_inodes=15595,mode=755)

    proc on /proc type proc (rw,relatime)

    sysfs on /sys type sysfs (rw,relatime)

    none on /dev type tmpfs (rw,relatime,size=8k,nr_inodes=8192,mode=755)

    /dev/mmcblk0p1 on /media/mmcblk0p1 type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

    devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620)

    usbfs on /proc/bus/usb type usbfs (rw,relatime)

    tmpfs on /var/volatile type tmpfs (rw,relatime,size=16384k)

    tmpfs on /dev/shm type tmpfs (rw,relatime,mode=777)

    tmpfs on /media/ram type tmpfs (rw,relatime,size=16384k)

     

    ------------------------------------------With ext3 --------------------------------

    root@ti8168-evm:/media/mmcblk0p2# sync ; time dd if=/dev/zero of=output2.dat cou

    nt=200 bs=1M; echo; time sync

    200+0 records in

    200+0 records out

    real    0m 53.79s

    user    0m 0.00s

    sys     0m 1.41s

     

    real    0m 10.60s

    user    0m 0.02s

    sys     0m 0.00s

    root@ti8168-evm:/media/mmcblk0p2# mount

    rootfs on / type rootfs (rw)

    172.24.179.98:/groups/psp/anil/netra/nfs_root on / type nfs (rw,relatime,vers=3,rsize=262144,wsize=262144,namlen=255,hard,nolock,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=172.24.179.98,mountvers=3,mountproto=tcp,local_lock=all,addr=172.24.179.98)

    devtmpfs on /dev type devtmpfs (rw,relatime,size=62380k,nr_inodes=15595,mode=755)

    proc on /proc type proc (rw,relatime)

    sysfs on /sys type sysfs (rw,relatime)

    none on /dev type tmpfs (rw,relatime,size=8k,nr_inodes=8192,mode=755)

    devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620)

    usbfs on /proc/bus/usb type usbfs (rw,relatime)

    tmpfs on /var/volatile type tmpfs (rw,relatime,size=16384k)

    tmpfs on /dev/shm type tmpfs (rw,relatime,mode=777)

    tmpfs on /media/ram type tmpfs (rw,relatime,size=16384k)

    /dev/mmcblk0p1 on /media/mmcblk0p1 type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

    /dev/mmcblk0p2 on /media/mmcblk0p2 type ext3 (rw,relatime,errors=continue,barrier=0,data=writeback)

     

    Regards

    Sriram