From: David S. Miller Date: Mon, 24 Sep 2018 04:55:26 +0000 (-0700) Subject: Merge branch 'netpoll-avoid-capture-effects-for-NAPI-drivers' X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=841dfa43788a309d353b3b7a81c85ed8d3eac130;p=linux.git Merge branch 'netpoll-avoid-capture-effects-for-NAPI-drivers' Eric Dumazet says: ==================== 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. This patch series take care of the first round, we will handle other drivers in future rounds. ==================== Signed-off-by: David S. Miller --- 841dfa43788a309d353b3b7a81c85ed8d3eac130