From 9e3cccd176b5ec6ff78693287fb03097e453e69c Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 4 Dec 2024 07:46:41 +0000 Subject: rxrpc: Fix CPU time starvation in I/O thread Starvation can happen in the rxrpc I/O thread because it goes back to the top of the I/O loop after it does any one thing without trying to give any other connection or call CPU time. Also, because it processes one call packet at a time, it tries to do the retransmission loop after each ACK without checking to see if there are other ACKs already in the queue that can update the SACK state. Fix this by: (1) Add a received-packet queue on each call. (2) Distribute packets from the master Rx queue to the individual call, conn and error queues and 'poking' calls to add them to the attend queue first thing in the I/O thread. (3) Go through all the attention-seeking connections and calls before going back to the top of the I/O thread. Each queue is extracted as a whole and then gone through so that new additions to insert themselves into the queue. (4) Make the call event handler go through all the packets currently on the call's rx_queue before transmitting and retransmitting DATA packets. (5) Drop the skb argument from the call event handler as this is now replaced with the rx_queue. Instead, keep track of whether we received a packet or an ACK for the tests that used to rely on that. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20241204074710.990092-14-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- include/trace/events/rxrpc.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/trace') diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index 71f07e726a90..28fa7be31ff8 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -120,6 +120,7 @@ EM(rxrpc_call_poke_conn_abort, "Conn-abort") \ EM(rxrpc_call_poke_error, "Error") \ EM(rxrpc_call_poke_idle, "Idle") \ + EM(rxrpc_call_poke_rx_packet, "Rx-packet") \ EM(rxrpc_call_poke_set_timeout, "Set-timo") \ EM(rxrpc_call_poke_start, "Start") \ EM(rxrpc_call_poke_timer, "Timer") \ @@ -128,6 +129,7 @@ #define rxrpc_skb_traces \ EM(rxrpc_skb_eaten_by_unshare, "ETN unshare ") \ EM(rxrpc_skb_eaten_by_unshare_nomem, "ETN unshar-nm") \ + EM(rxrpc_skb_get_call_rx, "GET call-rx ") \ EM(rxrpc_skb_get_conn_secured, "GET conn-secd") \ EM(rxrpc_skb_get_conn_work, "GET conn-work") \ EM(rxrpc_skb_get_last_nack, "GET last-nack") \ @@ -139,6 +141,7 @@ EM(rxrpc_skb_new_error_report, "NEW error-rpt") \ EM(rxrpc_skb_new_jumbo_subpacket, "NEW jumbo-sub") \ EM(rxrpc_skb_new_unshared, "NEW unshared ") \ + EM(rxrpc_skb_put_call_rx, "PUT call-rx ") \ EM(rxrpc_skb_put_conn_secured, "PUT conn-secd") \ EM(rxrpc_skb_put_conn_work, "PUT conn-work") \ EM(rxrpc_skb_put_error_report, "PUT error-rep") \ -- cgit v1.2.3