On 3/9/2021 10:19 AM, Ciara Loftus wrote:
This commit introduces support for preferred busy polling
to the AF_XDP PMD. This feature aims to improve single-core
performance for AF_XDP sockets under heavy load.
A new vdev arg is introduced called 'busy_budget' whose default
value is 64. busy_budget is the value supplied to the kernel
with the SO_BUSY_POLL_BUDGET socket option and represents the
busy-polling NAPI budget. To set the budget to a different value
eg. 256:
--vdev=net_af_xdp0,iface=eth0,busy_budget=256
Preferred busy polling is enabled by default provided a kernel with
version >= v5.11 is in use. To disable it, set the budget to zero.
The following settings are also strongly recommended to be used in
conjunction with this feature:
echo 2 | sudo tee /sys/class/net/eth0/napi_defer_hard_irqs
echo 200000 | sudo tee /sys/class/net/eth0/gro_flush_timeout
.. where eth0 is the interface being used by the PMD.
Signed-off-by: Ciara Loftus <ciara.lof...@intel.com>
<...>
--- a/doc/guides/rel_notes/release_21_05.rst
+++ b/doc/guides/rel_notes/release_21_05.rst
@@ -70,6 +70,10 @@ New Features
* Added command to display Rx queue used descriptor count.
``show port (port_id) rxq (queue_id) desc used count``
+* **Updated the AF_XDP driver.**
+
+ * Added support for preferred busy polling.
+
Can you please move the update after above the testpmd updates?
For more details the expected order is in the section comment.
+static int
+configure_preferred_busy_poll(struct pkt_rx_queue *rxq)
+{
+ int sock_opt = 1;
+ int fd = xsk_socket__fd(rxq->xsk);
+ int ret = 0;
+
+ ret = setsockopt(fd, SOL_SOCKET, SO_PREFER_BUSY_POLL,
+ (void *)&sock_opt, sizeof(sock_opt));
+ if (ret < 0) {
+ AF_XDP_LOG(DEBUG, "Failed to set SO_PREFER_BUSY_POLL\n");
+ goto err_prefer;
+ }
+
+ sock_opt = ETH_AF_XDP_DFLT_BUSY_TIMEOUT;
+ ret = setsockopt(fd, SOL_SOCKET, SO_BUSY_POLL, (void *)&sock_opt,
+ sizeof(sock_opt));
+ if (ret < 0) {
+ AF_XDP_LOG(DEBUG, "Failed to set SO_BUSY_POLL\n");
[1]
+ goto err_timeout;
+ }
+
+ sock_opt = rxq->busy_budget;
+ ret = setsockopt(fd, SOL_SOCKET, SO_BUSY_POLL_BUDGET,
+ (void *)&sock_opt, sizeof(sock_opt));
+ if (ret < 0) {
+ AF_XDP_LOG(DEBUG, "Failed to set SO_BUSY_POLL_BUDGET\n");
In above [1] and here, shouldn't the function return error, even the rollback is
successful.
I am thinking a case an invalid 'busy_budget' provided, like a very big number
or negative value.
+ } else {
+ AF_XDP_LOG(INFO, "Busy polling budget set to: %u\n",
+ rxq->busy_budget);
+ return 0;
+ }
+
+ /* setsockopt failure - attempt to restore xsk to default state and
+ * proceed without busy polling support.
+ */
+ sock_opt = 0;
+ ret = setsockopt(fd, SOL_SOCKET, SO_BUSY_POLL, (void *)&sock_opt,
+ sizeof(sock_opt));
+ if (ret < 0) {
+ AF_XDP_LOG(ERR, "Failed to unset SO_BUSY_POLL\n");
+ return -1;
+ }
+
+err_timeout:
+ sock_opt = 0;
+ ret = setsockopt(fd, SOL_SOCKET, SO_PREFER_BUSY_POLL,
+ (void *)&sock_opt, sizeof(sock_opt));
+ if (ret < 0) {
+ AF_XDP_LOG(ERR, "Failed to unset SO_PREFER_BUSY_POLL\n");
+ return -1;
+ }
+
+err_prefer:
+ rxq->busy_budget = 0;
+ return 0;
+}
+
<...>
