[ntp:questions] is USB inherently evil, or only if something else is on the bus?

David Taylor david-taylor at blueyonder.co.uk.invalid
Fri Aug 10 05:55:25 UTC 2012

On 09/08/2012 22:02, Rick Jones wrote:
> My recollections may not fit well with unruh's data (or perhaps they
> do), but interrupt coalescing is not completely correlated with
> interface speed.  It is a feature of implementation, not media.  Now,
> it is generally the case that interrupt coalescing appeared first in 1
> GbE NICs, and so the prior 10/100 Mbit/s didn't have it, but that
> doesn't necessarily mean that a 1 GbE NIC operating at 100 Mbit/s
> won't still have interrupt coalescing going.
> So I would think it isn't so much a matter of operating at 100 Mbit/s
> vs 1 Gbit/s as it is the interrupt coalescing settings.
> rick
> * of course since interrupt coalescing can be timing related and since
>    operating at 100 Mbit/s will have different timing than 1 Gbit/s...

Yes, Rick, my logic had been along the lines that an older 100 Mb/s card 
would /not/ have interrupt coalescing, whereas a 100 Mb/s card /might/. 
  I take your point about simply turning down the speed not turning off 
the feature.
("Card" here includes motherboard interfaces.)
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