On 22 Aug 2019, at 19:12, Ilya Maximets wrote:
Tx code doesn't clear the descriptors' status after cleaning.
So, if the budget is larger than number of used elems in a ring, some
descriptors will be accounted twice and xsk_umem_complete_tx will move
prod_tail far beyond the prod_head breaking the completion queue ring.
Fix that by limiting the number of descriptors to clean by the number
of used descriptors in the tx ring.
'ixgbe_clean_xdp_tx_irq()' function refactored to look more like
'ixgbe_xsk_clean_tx_ring()' since we're allowed to directly use
'next_to_clean' and 'next_to_use' indexes.
Fixes: 8221c5eba8c1 ("ixgbe: add AF_XDP zero-copy Tx support")
Signed-off-by: Ilya Maximets <i.maximets@xxxxxxxxxxx>
---
Version 3:
* Reverted some refactoring made for v2.
* Eliminated 'budget' for tx clean.
* prefetch returned.
Version 2:
* 'ixgbe_clean_xdp_tx_irq()' refactored to look more like
'ixgbe_xsk_clean_tx_ring()'.
drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 29
++++++++------------
1 file changed, 11 insertions(+), 18 deletions(-)
Did some test with and without the fix applied. For PVP the results are
a little different depending on the packet size (note this is a single
run, no deviation).
For the same physical port in and out it’s faster! Note this was OVS
AF_XDP using a XENA tester at 10G wire speed.
+--------------------------------------------------------------------------------+
| Physical to Virtual to Physical test, L3 flows[port redirect]
|
+-----------------+--------------------------------------------------------------+
| | Packet size
|
+-----------------+--------+--------+--------+--------+--------+--------+--------+
| Number of flows | 64 | 128 | 256 | 512 | 768 | 1024
| 1514 |
+-----------------+--------+--------+--------+--------+--------+--------+--------+
| [NO FIX] 1000 | 739161 | 700091 | 690034 | 659894 | 618128 | 594223
| 537504 |
+-----------------+--------+--------+--------+--------+--------+--------+--------+
| [FIX] 1000 | 742317 | 708391 | 689952 | 658034 | 626056 | 587653
| 530885 |
+-----------------+--------+--------+--------+--------+--------+--------+--------+
+--------------------------------------------------------------------------------------+
| Physical loopback test, L3 flows[port redirect]
|
+-----------------+--------------------------------------------------------------------+
| | Packet size
|
+-----------------+---------+---------+---------+---------+---------+---------+--------+
| Number of flows | 64 | 128 | 256 | 512 | 768 |
1024 | 1514 |
+-----------------+---------+---------+---------+---------+---------+---------+--------+
| [NO FIX] 1000 | 2573298 | 2227578 | 2514318 | 2298204 | 1081861 |
1015173 | 788081 |
+-----------------+---------+---------+---------+---------+---------+---------+--------+
| [FIX] 1000 | 3343188 | 3234993 | 3151833 | 2349597 | 1586276 |
1197304 | 814854 |
+-----------------+---------+---------+---------+---------+---------+---------+--------+
Tested-by: Eelco Chaudron <echaudro@xxxxxxxxxx>
