[OLPC-devel] Re: [One Laptop Per Child] #68: Network adapter causes 20% slowdown

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#68: Network adapter causes 20% slowdown
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 Reporter:  yoshiki at squeakland.org  |        Owner:  jg 
     Type:  defect                  |       Status:  new
 Priority:  normal                  |    Milestone:     
Component:  kernel                  |   Resolution:     
 Keywords:                          |  
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Comment (by arnd):

 Replying to [comment:3 krstic]:

 I when working on the mcs7830 usbnet driver, I saw a number of bad effects
 on the OLPC board:

 * The status interrupt keeps rearming itself, which results in an
 interrupt storm. Please watch your /proc/interrupts file to
 see how many USB interrupts you get on an idle system with and without the
 network adapter.

 * In some configurations, my adapter is rather unstable and generates
 error packets even if there is no data being transferred.
 Using an active hub solved that for me. Please attach the output of
 'ifconfig' to see if you have errors.

 * The usbnet infrastructure is not as optimal as it could be and uses lots
 of cycles in softirq context. I could never manage to transfer more than
 7MB/s because of that. It's not directly related to this problem, but we
 may want to profile this anyway.

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Ticket URL: <http://dev.laptop.org/ticket/68#comment:4>
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