[vdr] power consumption, powertop and wakups per second with a af9015 device, vp7045, and various plugins

Antti Palosaari crope at iki.fi
Tue Mar 24 23:44:28 CET 2009


Heinrich Langos wrote:
> Moikka Antti,
> 
>> vp7045 does not have PID-filters.
>> I think difference comes from different USB-transfer settings. vp7045  
>> uses BULK packet size 4096 and af9015 uses BULK packet size 512 for  
>> USB2.0 and BULK packet size 64 for USB1.1. Therefore af9015 sends 8  
>> times more packets than vp7045 (I guess).
>>
>> One thing more you can test - use USB1.1. To force USB1.1 remove USB2.0  
>> driver by rmmod ehci_hcd. After that plug af9015 stick and look from  
>> logs it detects USB1.1 and uses PID-filters. af9015 driver now uses  
>> smaller packet size for transfer that can change load (bigger?).

> seems you are right. The transfer with PID filter in usb 1.1 causes
> about 30% load in contrast to 19% with usb 2.0
> 
> is there a way to increase the packet size for those bulk transfers? 
> for usb 2.0? for 1.1?

Actually AF9015 chip offers registers to configure packet size. But 
those which are now used are default ones and rather many devices (other 
than af9015) are using just same. That's why I am not sure if I want 
change those to bigger ones.

I will make test version that uses 4k packets for your tests. If it 
resolves problem then we should consider for example adding module param 
for setting desirable packet size. I will inform you when test version 
is ready - It takes day or two.

regards
Antti
-- 
http://palosaari.fi/



More information about the vdr mailing list