From: Christopher Faulet <cfaulet@haproxy.com>
Date: Mon, 4 Dec 2023 13:48:52 +0000 (+0100)
Subject: MINOR: mux-pt: Add global option to enable/disable zero-copy forwarding
X-Git-Tag: v2.9.0~12
X-Git-Url: http://git.haproxy.org/?a=commitdiff_plain;h=eccef69137008d315118799d7ae1c7e8c3450ff5;p=haproxy-2.9.git

MINOR: mux-pt: Add global option to enable/disable zero-copy forwarding

tune.pt.zero-copy-forwarding parameter can now be used to enable or disable
the zero-copy fast-forwarding for the PT mux only. It is enabled ('on') by
default. It can be disabled by setting the parameter to 'off'. In this case,
this disables receive and send side.
---

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 670b2e8..b3bf728 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -1211,6 +1211,7 @@ The following keywords are supported in the "global" section :
    - tune.pipesize
    - tune.pool-high-fd-ratio
    - tune.pool-low-fd-ratio
+   - tune.pt.zero-copy-forwarding
    - tune.quic.frontend.conn-tx-buffers.limit
    - tune.quic.frontend.max-idle-timeout
    - tune.quic.frontend.max-streams-bidi
@@ -2921,6 +2922,8 @@ tune.disable-zero-copy-forwarding
   Thanks to this directive, it is possible to disable this optimization. Note
   it also disable any kernel tcp splicing.
 
+  See also: tune.pt.zero-copy-forwarding
+
 tune.events.max-events-at-once <number>
   Sets the number of events that may be processed at once by an asynchronous
   task handler (from event_hdl API). <number> should be included between 1
@@ -3347,6 +3350,14 @@ tune.pool-low-fd-ratio <number>
   use before we stop putting connection into the idle pool for reuse. The
   default is 20.
 
+tune.pt.zero-copy-forwarding { on | off }
+  Enables ('on') of disabled ('off') the zero-copy forwarding of data for the
+  pass-through multiplexer. To be used, the kernel splicing must also be
+  configured. It is enabled by default.
+
+  See also: tune.disable-zero-copy-forwarding, option splice-auto,
+            option splice-request and option splice-response
+
 tune.quic.frontend.conn-tx-buffers.limit <number>
   This settings defines the maximum number of buffers allocated for a QUIC
   connection on data emission. By default, it is set to 30. QUIC buffers are
diff --git a/src/mux_pt.c b/src/mux_pt.c
index 11f4705..3284286 100644
--- a/src/mux_pt.c
+++ b/src/mux_pt.c
@@ -12,6 +12,7 @@
 
 #include <haproxy/api.h>
 #include <haproxy/buf.h>
+#include <haproxy/cfgparse.h>
 #include <haproxy/connection.h>
 #include <haproxy/pipe.h>
 #include <haproxy/stconn.h>
@@ -654,6 +655,11 @@ static int mux_pt_fastfwd(struct stconn *sc, unsigned int count, unsigned int fl
 
 	TRACE_ENTER(PT_EV_RX_DATA, conn, sc, 0, (size_t[]){count});
 
+	if (global.tune.no_zero_copy_fwd & NO_ZERO_COPY_FWD_PT) {
+		se_fl_clr(ctx->sd, SE_FL_MAY_FASTFWD);
+		goto end;
+	}
+
 	se_fl_clr(ctx->sd, SE_FL_RCV_MORE | SE_FL_WANT_ROOM);
 	conn->flags &= ~CO_FL_WAIT_ROOM;
 	sdo = mux_pt_opposite_sd(ctx);
@@ -810,6 +816,35 @@ static int mux_pt_sctl(struct stconn *sc, enum mux_sctl_type mux_sctl, void *out
 	}
 }
 
+/* config parser for global "tune.pt.zero-copy-forwarding" */
+static int cfg_parse_pt_zero_copy_fwd(char **args, int section_type, struct proxy *curpx,
+				      const struct proxy *defpx, const char *file, int line,
+				      char **err)
+{
+	if (too_many_args(1, args, err, NULL))
+		return -1;
+
+	if (strcmp(args[1], "on") == 0)
+		global.tune.no_zero_copy_fwd &= ~NO_ZERO_COPY_FWD_PT;
+	else if (strcmp(args[1], "off") == 0)
+		global.tune.no_zero_copy_fwd |= NO_ZERO_COPY_FWD_PT;
+	else {
+		memprintf(err, "'%s' expects 'on' or 'off'.", args[0]);
+		return -1;
+	}
+	return 0;
+}
+
+
+/* config keyword parsers */
+static struct cfg_kw_list cfg_kws = {ILH, {
+	{ CFG_GLOBAL, "tune.pt.zero-copy-forwarding", cfg_parse_pt_zero_copy_fwd },
+	{ 0, NULL, NULL }
+}};
+
+INITCALL1(STG_REGISTER, cfg_register_keywords, &cfg_kws);
+
+
 /* The mux operations */
 const struct mux_ops mux_tcp_ops = {
 	.init = mux_pt_init,