From 8b5823ea437624b53ecf084b6dd582760f110394 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 4 Dec 2024 07:46:35 +0000 Subject: [PATCH] rxrpc: Request an ACK on impending Tx stall Set the REQUEST-ACK flag on the DATA packet we're about to send if we're about to stall transmission because the app layer isn't keeping up supplying us with data to transmit. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20241204074710.990092-8-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- include/trace/events/rxrpc.h | 1 + net/rxrpc/ar-internal.h | 2 +- net/rxrpc/output.c | 7 ++++++- net/rxrpc/proc.c | 5 +++-- 4 files changed, 11 insertions(+), 4 deletions(-) diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index 62064f63d6eb8..d86b5f07d2926 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -452,6 +452,7 @@ #define rxrpc_req_ack_traces \ EM(rxrpc_reqack_ack_lost, "ACK-LOST ") \ + EM(rxrpc_reqack_app_stall, "APP-STALL ") \ EM(rxrpc_reqack_more_rtt, "MORE-RTT ") \ EM(rxrpc_reqack_no_srv_last, "NO-SRVLAST") \ EM(rxrpc_reqack_old_rtt, "OLD-RTT ") \ diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index fcdfbc1d5aafa..d0fd37bdcfe9c 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -110,7 +110,7 @@ struct rxrpc_net { atomic_t stat_tx_acks[256]; atomic_t stat_rx_acks[256]; - atomic_t stat_why_req_ack[7]; + atomic_t stat_why_req_ack[8]; atomic_t stat_io_loop; }; diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index 50d5f2a02458a..b93a5d50be3e4 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -330,7 +330,7 @@ static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_t struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base; enum rxrpc_req_ack_trace why; struct rxrpc_connection *conn = call->conn; - bool last; + bool last, more; u8 flags; _enter("%x,{%d}", txb->seq, txb->len); @@ -345,6 +345,9 @@ static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_t flags = txb->flags & RXRPC_TXBUF_WIRE_FLAGS; last = txb->flags & RXRPC_LAST_PACKET; + more = (!list_is_last(&txb->call_link, &call->tx_buffer) || + !list_empty(&call->tx_sendmsg)); + /* If our RTT cache needs working on, request an ACK. Also request * ACKs if a DATA packet appears to have been lost. * @@ -366,6 +369,8 @@ static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_t why = rxrpc_reqack_more_rtt; else if (ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), ktime_get_real())) why = rxrpc_reqack_old_rtt; + else if (!last && !more) + why = rxrpc_reqack_app_stall; else goto dont_set_request_ack; diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c index cdf32f0d8e0ea..ce4d48bdfbe9e 100644 --- a/net/rxrpc/proc.c +++ b/net/rxrpc/proc.c @@ -520,10 +520,11 @@ int rxrpc_stats_show(struct seq_file *seq, void *v) atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_IDLE]), atomic_read(&rxnet->stat_rx_acks[0])); seq_printf(seq, - "Why-Req-A: acklost=%u mrtt=%u ortt=%u\n", + "Why-Req-A: acklost=%u mrtt=%u ortt=%u stall=%u\n", atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_ack_lost]), atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_more_rtt]), - atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_old_rtt])); + atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_old_rtt]), + atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_app_stall])); seq_printf(seq, "Why-Req-A: nolast=%u retx=%u slows=%u smtxw=%u\n", atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_no_srv_last]), -- 2.50.1