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-rw-r--r--include/net/xdp_sock.h7
-rw-r--r--net/xdp/xsk.c18
2 files changed, 25 insertions, 0 deletions
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 7dd0df2f6f8e..f83128007fb0 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -63,6 +63,13 @@ struct xdp_sock {
struct xsk_queue *tx ____cacheline_aligned_in_smp;
struct list_head tx_list;
+ /* record the number of tx descriptors sent by this xsk and
+ * when it exceeds MAX_PER_SOCKET_BUDGET, an opportunity needs
+ * to be given to other xsks for sending tx descriptors, thereby
+ * preventing other XSKs from being starved.
+ */
+ u32 tx_budget_spent;
+
/* Protects generic receive. */
spinlock_t rx_lock;
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index ba070fd37d24..ae9f8cb611f6 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -33,6 +33,7 @@
#include "xsk.h"
#define TX_BATCH_SIZE 32
+#define MAX_PER_SOCKET_BUDGET (TX_BATCH_SIZE)
static DEFINE_PER_CPU(struct list_head, xskmap_flush_list);
@@ -423,16 +424,25 @@ EXPORT_SYMBOL(xsk_tx_release);
bool xsk_tx_peek_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc)
{
+ bool budget_exhausted = false;
struct xdp_sock *xs;
rcu_read_lock();
+again:
list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list) {
+ if (xs->tx_budget_spent >= MAX_PER_SOCKET_BUDGET) {
+ budget_exhausted = true;
+ continue;
+ }
+
if (!xskq_cons_peek_desc(xs->tx, desc, pool)) {
if (xskq_has_descs(xs->tx))
xskq_cons_release(xs->tx);
continue;
}
+ xs->tx_budget_spent++;
+
/* This is the backpressure mechanism for the Tx path.
* Reserve space in the completion queue and only proceed
* if there is space in it. This avoids having to implement
@@ -446,6 +456,14 @@ bool xsk_tx_peek_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc)
return true;
}
+ if (budget_exhausted) {
+ list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list)
+ xs->tx_budget_spent = 0;
+
+ budget_exhausted = false;
+ goto again;
+ }
+
out:
rcu_read_unlock();
return false;