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SubjectRe: peeking the netdevice queue
Date
> 	In my COSA driver (www.fi.muni.cz/~kas/cosa) it would help
> to improve the effectivity of the driver, because in the end-of-transmit
> interrupt the driver should tell the device if it has another packet
> ready for transmit. The present driver tells the card there are no more
> packets waiting for transmit and lets the dev->hard_start_xmit() to start
> the new transmit later.

As soon as you've done mark_bh(NET_BH) and returned from your IRQ you will
get called from the bottom half handler. The tiny delay there isn't normally
a problem because cards go to "busy" state when their own buffers are full
which is usually at least 2 frames, you therefore have a whole frame time
to load the next packet.

Its not always true. The Z85230 driver it isnt true for, and that simply
keeps hold of a single "next packet" buffer. Thats sufficient to keep it
well fed and happy.

> I have looked at other drivers - for example the 3c59x.c
> implements its own internal queue of packets waiting for transmit

That one is well overkill

Alan


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