From: Frédéric Lécaille <flecaille@haproxy.com>
Date: Thu, 30 Jun 2022 09:28:56 +0000 (+0200)
Subject: MINOR: quic: Improvements for the datagrams receipt
X-Git-Tag: v2.7-dev2~168
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1b0707f3e7ee496e4398f87e8607909a7edcafbf;p=thirdparty%2Fhaproxy.git

MINOR: quic: Improvements for the datagrams receipt

First we add a loop around recfrom() into the most low level I/O handler
quic_sock_fd_iocb() to collect as most as possible datagrams before during
its tasklet wakeup with a limit: we recvfrom() at most "maxpollevents"
datagrams. Furthermore we add a local task list into the datagram handler
quic_lstnr_dghdlr() which is passed to the first datagrams parser qc_lstnr_pkt_rcv().
This latter parser only identifies the connection associated to the datagrams then
wakeup the highest level packet parser I/O handlers (quic_conn.*io_cb()) after
it is done, thanks to the call to tasklet_wakeup_after() which replaces from now on
the call to tasklet_wakeup(). This should reduce drastically the latency and the
chances to fulfil the RX buffers at the QUIC connections level as reported in
GH #1737 by Tritan.

These modifications depend on this commit:
    "MINOR: task: Add tasklet_wakeup_after()"

Must be backported to 2.6 with the previous commit.
---

diff --git a/src/quic_sock.c b/src/quic_sock.c
index f8590f8462..51d887a2cc 100644
--- a/src/quic_sock.c
+++ b/src/quic_sock.c
@@ -275,6 +275,7 @@ void quic_sock_fd_iocb(int fd)
 	socklen_t saddrlen;
 	struct quic_dgram *new_dgram;
 	unsigned char *dgram_buf;
+	int max_dgrams;
 
 	BUG_ON(!l);
 
@@ -291,6 +292,8 @@ void quic_sock_fd_iocb(int fd)
 
 	buf = &rxbuf->buf;
 
+	max_dgrams = global.tune.maxpollevents;
+ start:
 	/* Try to reuse an existing dgram. Note that there is alway at
 	 * least one datagram to pick, except the first time we enter
 	 * this function for this <rxbuf> buffer.
@@ -352,6 +355,8 @@ void quic_sock_fd_iocb(int fd)
 		b_del(buf, ret);
 	}
 	new_dgram = NULL;
+	if (--max_dgrams > 0)
+		goto start;
  out:
 	pool_free(pool_head_quic_dgram, new_dgram);
 	MT_LIST_APPEND(&l->rx.rxbuf_list, &rxbuf->mt_list);
diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 018975dd31..ce4a2f9704 100644
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -5236,7 +5236,7 @@ static inline int quic_padding_check(const unsigned char *buf,
  */
 static void qc_lstnr_pkt_rcv(unsigned char *buf, const unsigned char *end,
                              struct quic_rx_packet *pkt, int first_pkt,
-                             struct quic_dgram *dgram)
+                             struct quic_dgram *dgram, struct list **tasklist_head)
 {
 	unsigned char *beg, *payload;
 	struct quic_conn *qc, *qc_to_purge = NULL;
@@ -5610,7 +5610,7 @@ static void qc_lstnr_pkt_rcv(unsigned char *buf, const unsigned char *end,
 	 */
 	conn_ctx = qc->xprt_ctx;
 	if (conn_ctx)
-		tasklet_wakeup(conn_ctx->wait_event.tasklet);
+		*tasklist_head = tasklet_wakeup_after(*tasklist_head, conn_ctx->wait_event.tasklet);
 
  drop_no_conn:
 	if (drop_no_conn)
@@ -6489,6 +6489,7 @@ struct task *quic_lstnr_dghdlr(struct task *t, void *ctx, unsigned int state)
 	struct quic_dghdlr *dghdlr = ctx;
 	struct quic_dgram *dgram;
 	int first_pkt = 1;
+	struct list *tasklist_head = NULL;
 
 	while ((dgram = MT_LIST_POP(&dghdlr->dgrams, typeof(dgram), mt_list))) {
 		pos = dgram->buf;
@@ -6503,7 +6504,7 @@ struct task *quic_lstnr_dghdlr(struct task *t, void *ctx, unsigned int state)
 			LIST_INIT(&pkt->qc_rx_pkt_list);
 			pkt->time_received = now_ms;
 			quic_rx_packet_refinc(pkt);
-			qc_lstnr_pkt_rcv(pos, end, pkt, first_pkt, dgram);
+			qc_lstnr_pkt_rcv(pos, end, pkt, first_pkt, dgram, &tasklist_head);
 			first_pkt = 0;
 			pos += pkt->len;
 			quic_rx_packet_refdec(pkt);