With the PCIe devices, it looks as if issuing a TX command while

there is already a transmission in progress has no effect. In other
words, if you send two packets in rapid succession, the second one may
end up sitting in the TX DMA ring until another transmit command is
issued later in the future. Basically, if re_txeof() sees that there
are still descriptors outstanding, it needs to manually resume the
TX DMA channel by issuing another TX command to make sure all
transmissions are flushed out. (The PCI devices seem to keep the
TX channel moving until all descriptors have been consumed. I'm not
sure why the PCIe devices behave differently.)

From wpaul@FreeBSD

0 files changed, 0 insertions, 0 deletions