On Tuesday 25 March 2014 10:16:28 Florian Fainelli wrote:
>
> Ok, well that's really unfortunate, to achieve the best of everything,
> the workaround should probably look like:
>
> - keep reclaiming TX buffers in ndo_start_xmit() in case you push more
> packets to the NICs than your timer can free
> - reclaim TX buffers in NAPI poll() context for "symetrical" workloads
> where e.g: TCP ACKs received allow you to complete TX buffers
> - have a timer like you suggest which should help with transmit only
> workloads at a slow rate
Yes, that is what I was thinking, but with orphaning the tx skbs,
we can probably be a little smarter. Note that in order to check
the state of the queue, we have to do a read from uncached memory,
since the hardware also doesn't support cache coherent DMA.
We don't want to do that too often.
Arnd
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