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96e0fa94c7
It is unused by default and upstream is trying to remove it as it has negative effects when the driver is under load. Upstream explanation: netpoll: avoid capture effects for NAPI drivers As diagnosed by Song Liu, ndo_poll_controller() can be very dangerous on loaded hosts, since the cpu calling ndo_poll_controller() might steal all NAPI contexts (for all RX/TX queues of the NIC). This capture, showing one ksoftirqd eating all cycles can last for unlimited amount of time, since one cpu is generally not able to drain all the queues under load. It seems that all networking drivers that do use NAPI for their TX completions, should not provide a ndo_poll_controller() : Most NAPI drivers have netpoll support already handled in core networking stack, since netpoll_poll_dev( uses poll_napi(dev) to iterate through registered NAPI contexts for a device. Signed-off-by: Rosen Penev <rosenp@gmail.com> |
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