[Fwd: SD card speed]

[Marc van Woerkom]

I did some more tests.

Using smaller blocksizes (newfs_msdosfs -b 4096) yields even slower write
transfer rates. It looks like there are only 7 transfers per seconds, 
thus if
the blocksize is smaller, less data is shoveled over.

      tty             da2             cpu
 tin tout  KB/t tps  MB/s  us ni sy in id
   0   65  4.00   7  0.03  14  0  6  2 78
   0  181  4.00   7  0.03  11  0  7  2 80
   0   89  4.00   7  0.03  13  0  8  4 75
   0   69  4.00   7  0.03   9  0  9  2 80
   0   76  4.00   6  0.02  16  0  4  4 77
   0   71  4.00   7  0.03  12  0 10  3 75
   0  132  4.00   7  0.03   6  0 16  3 75
   0   76  4.00   7  0.03  34  0  8  4 54
   0   78  4.00   7  0.03   8  0  5  2 86
   0  152  4.00   7  0.03  14  0  5  1 80
   0   87  4.00   6  0.02  12  0  6  1 81
   0   80  4.00   7  0.03   9  0  7  3 80

It doesn't seem to matter if it is FAT or FAT32.

However if I format the SD card as UFS2 system, the card is fast:

[root at hokage /]# fdisk /dev/da2
******* Working on device /dev/da2 *******
parameters extracted from in-core disklabel are:
cylinders=472 heads=64 sectors/track=32 (2048 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=472 heads=64 sectors/track=32 (2048 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 32, size 966624 (471 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 471/ head 63/ sector 32
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>

     tty             da2             cpu
 tin tout  KB/t tps  MB/s  us ni sy in id
  27   55  1.45   1  0.00  12  0  7  2 79
   0  162 128.00  20  2.50   8  0  9  4 80
   0   70 128.00  23  2.87   5  0  9  3 83
   0   66 128.00  21  2.62  12  0  7  1 80
   0   44 128.00  24  3.00   9  0  8  1 83
   0   72 128.00  22  2.75   7  0  5  1 87
   0  127 128.00  23  2.87  12  0 13  3 71
   0   66 128.00  23  2.87   5  0  7  4 84
   0   81 128.00  23  2.87  17  0  8  4 71
   0   66 128.00  23  2.87   7  0  9  4 80
   0   70 128.00  22  2.75  12  0 11  3 74
   0   90 128.00  23  2.87  10  0  8  2 80
 136   81 128.00  20  2.50   9  0  9  2 80

Thus the slowdown seems to be related to using a FAT filesystem on
that SD card.

Last thing I have to test is what happens, if I partition/format that
SD card under Windows.

Regards,
Marc