[CentOS] Re: usb irq problem

Scott Silva ssilva at sgvwater.com
Wed Sep 24 15:27:11 UTC 2008


on 9-24-2008 6:42 AM kira laucas spake the following:
> 
> 
> On Wed, Sep 24, 2008 at 5:39 PM, nate 
> <centos at linuxpowered.net 
> <mailto:centos at linuxpowered.net>> wrote:
> 
> 
> 
>     http://www.linuxtopia.org/online_books/linux_kernel/kernel_configuration/re18.html
> 
>     By default, the kernel attempts to detect and disable unhandled
>     interrupt sources because they can cause problems with the
>     responsiveness of the rest of the kernel if left unchecked.
>     This option will disable this logic.
> 
>     just for curiosity, is this option removed  in the latest 2.6.26.5
>     <http://2.6.26.5> kernel ? because i experimented with compiling a
>     custom kernel and did not ever receive the message . anyway i am
>     running centos without any problem now and i am glad about it.
> 
>     Replace the hardware, get better quality stuff. Since this
>     is USB, get a PCI USB expansion board see if that helps.
>     About a year ago I bought a USB 2.0 PCI card for one of
>     my older systems, was about $20 I think.
> 
> now that you have mentioned it, i have noticed recently that my desktop 
> motherboard usb port has gone slower. i mean previously i used to get 
> 28-30 MB/s transfer speed with my external usb drive. but now the max i 
> get is 10MB/s . i have tested the external drive on my friend's laptop 
> and to my surprise it transferred with 25MB/s ! is it any indication of 
> any potentially disastrous hardware failure issue ?
> 
USB is interrupt driven. If the system has trouble responding to the 
interrupts quick enough, it will slow down the transfers. Too bad the USB 
designers didn't make it DMA driven like firewire. But then it was designed to 
be cheaper.


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