Subject: caracter device speed, the second
To: None <Peter.Berg@ww.tu-freiberg.de>
From: Peter Berg <root@Kyra.FutureGroove.de>
List: port-arm32
Date: 02/22/1997 21:00:02
> Hi,
> 
> what's the highest speed a character device can run at ?
> 
> I've tested the speed of my driver with a self written test program an I get
> as highest speed about 380KB/sec.
                         ^^^^^^^^^^

oops !

This seems to be caused by a calculation error. I tried a

	cat /dev/spdif > testout

for 5 seconds and got a file with a size of about 3.5MB. This equals a speed
of about 600KB and I think this is limited by the ffs ATM.

The new (and correct, I hope) results of my test prog. look like

#####################################################################################

S/PDIF device test

--- block read test ---

 read ten 10240KB blocks  speed : -1 Kb/sec  bytes/block: 262144
 read ten  5120KB blocks  speed : 3495253 Kb/sec  bytes/block: 262144
 read ten  2560KB blocks  speed : 3495253 Kb/sec  bytes/block: 262144
 read ten  1280KB blocks  speed : 3495253 Kb/sec  bytes/block: 262144
 read ten   640KB blocks  speed : 3542486 Kb/sec  bytes/block: 262144
 read ten   256KB blocks  speed : 3495253 Kb/sec  bytes/block: 262144

--- continous block read test ---
/dev/null speed test

 blocksize : 4096 bytes

real bytes read 0
time for test  : 0.300000 sec
Kbytes read    : 20480
transfer speed : 68266.664062 Kbyte/sec

/dev/spdif speed test

 blocksize : 5 bytes
time for test  : 0.350000 sec
Kbytes read    : 25
transfer speed : 71.428574 Kbyte/sec

 blocksize : 512 bytes
time for test  : 0.950000 sec
Kbytes read    : 2560
transfer speed : 2694.736816 Kbyte/sec

 blocksize : 2048 bytes
time for test  : 2.890000 sec
Kbytes read    : 10240
transfer speed : 3543.252441 Kbyte/sec

 blocksize : 4096 bytes
time for test  : 5.620000 sec
Kbytes read    : 20480
transfer speed : 3644.128174 Kbyte/sec


###################################################################################


3.5MB/sec ! Could this be possible or points me this to another bug in the
code ??




Ciao, Peter

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|                                                                          |
|                            >>> FutureGroove <<<                          |
|                                                                          |
| Peter Berg                                       Music production &      |
|                                                  softwaredevelopment     |
| w3: http://www.ww.tu-freiberg.de/~pberg                                  |
| email: Peter.Berg@ww.tu-freiberg.de                                      |
|                                           part time system administrator |
|                                                   at *.ww.tu-freiberg.de |
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