linux-stable/drivers/net/ethernet/netronome
Jakub Kicinski d38df0d364 nfp: avoid reading TX queue indexes from the device
Reading TX queue indexes from the device memory on each interrupt
is expensive.  It's doubly expensive with XDP running since we have
two TX rings to check there.  If the software indexes indicate that
the TX queue is completely empty, however, we don't need to look at
the device completion index at all.

The queuing CPU is doing a wmb() before kicking the device TX so
we should be safe to assume on the CPU handling the completions will
never see old value of the software copy of the index.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-30 22:37:00 -04:00
..
nfp nfp: avoid reading TX queue indexes from the device 2017-04-30 22:37:00 -04:00
Kconfig nfp: rename the driver and add new main file 2017-02-10 15:52:24 -05:00
Makefile nfp: rename the driver and add new main file 2017-02-10 15:52:24 -05:00