On 01/08/2014 10:09 AM, Eric Dumazet wrote:
In normal networking land, when a host A sends frames to host B,
nothing prevents A to pause the traffic to B if B is dropping packets
under stress.
A physical NIC do not use a workqueue to refill its RX queue but uses
the following strategy :
0) Pre filling of RX ring buffer with N frames. This can use GFP_KERNEL
allocations with all needed (sleep/retry/shout) logic...
1) IRQ is handled.
2) Can we allocate a new buffer (GFP_ATOMIC) ?
If yes, we accept the frame,
and post the new buffer for the 'next frame'
If no, we drop the frame and recycle the memory for next round.
and increment a suitably specific statistic so someone trying
to diagnose performance/other problems can know we dropped the frame.
rick jones
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