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0f7b182f2f

Stefan Eissing

2025-12-19

SUCCESS Duration: 197s

Subject

ngtcp2: retune window sizes

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

lib/vquic/curl_ngtcp2.c +41 -13

lib/vquic/curl_ngtcp2.c+41 -13

@@ -78,8 +78,11 @@
	/* A stream window is the maximum amount we need to buffer for
	* each active transfer.
	* Chunk size is large enough to take a full DATA frame */
-	#define H3_STREAM_WINDOW_SIZE (64 * 1024)
-	#define H3_STREAM_CHUNK_SIZE (16 * 1024)
+	#define H3_STREAM_WINDOW_SIZE_INITIAL (32 * 1024)
+	#define H3_STREAM_WINDOW_SIZE_MAX (10 * 1024 * 1024)
+	#define H3_CONN_WINDOW_SIZE_MAX (100 * H3_STREAM_WINDOW_SIZE_MAX)
+
+	#define H3_STREAM_CHUNK_SIZE (64 * 1024)
	#if H3_STREAM_CHUNK_SIZE < NGTCP2_MAX_UDP_PAYLOAD_SIZE
	#error H3_STREAM_CHUNK_SIZE smaller than NGTCP2_MAX_UDP_PAYLOAD_SIZE
	#endif
@@ -89,12 +92,11 @@
	* The benefit of the pool is that stream buffer to not keep
	* spares. Memory consumption goes down when streams run empty,
	* have a large upload done, etc. */
-	#define H3_STREAM_POOL_SPARES \
-	(H3_STREAM_WINDOW_SIZE / H3_STREAM_CHUNK_SIZE) / 2
+	#define H3_STREAM_POOL_SPARES 2
	/* Receive and Send max number of chunks just follows from the
	* chunk size and window size */
	#define H3_STREAM_SEND_CHUNKS \
-	(H3_STREAM_WINDOW_SIZE / H3_STREAM_CHUNK_SIZE)
+	(H3_STREAM_WINDOW_SIZE_MAX / H3_STREAM_CHUNK_SIZE)

	/*
	* Store ngtcp2 version info in this buffer.
@@ -131,7 +133,6 @@ struct cf_ngtcp2_ctx {
	struct bufc_pool stream_bufcp; /* chunk pool for streams */
	struct dynbuf scratch; /* temp buffer for header construction */
	struct uint_hash streams; /* hash `data->mid` to `h3_stream_ctx` */
-	size_t max_stream_window; /* max flow window for one stream */
	uint64_t used_bidi_streams; /* bidi streams we have opened */
	uint64_t max_bidi_streams; /* max bidi streams we can open */
	size_t earlydata_max; /* max amount of early data supported by
@@ -158,7 +159,6 @@ static void cf_ngtcp2_ctx_init(struct cf_ngtcp2_ctx *ctx)
	DEBUGASSERT(!ctx->initialized);
	ctx->qlogfd = -1;
	ctx->version = NGTCP2_PROTO_VER_MAX;
-	ctx->max_stream_window = H3_STREAM_WINDOW_SIZE;
	Curl_bufcp_init(&ctx->stream_bufcp, H3_STREAM_CHUNK_SIZE,
	H3_STREAM_POOL_SPARES);
	curlx_dyn_init(&ctx->scratch, CURL_MAX_HTTP_HEADER);
@@ -235,6 +235,7 @@ struct h3_stream_ctx {
	uint64_t error3; /* HTTP/3 stream error code */
	curl_off_t upload_left; /* number of request bytes left to upload */
	uint64_t download_unacked; /* bytes not acknowledged yet */
+	uint64_t window_size_max; /* max flow control window set for stream */
	int status_code; /* HTTP status code */
	CURLcode xfer_result; /* result from xfer_resp_write(_hd) */
	BIT(resp_hds_complete); /* we have a complete, final response */
@@ -279,6 +280,7 @@ static CURLcode h3_data_setup(struct Curl_cfilter *cf,
	Curl_bufq_initp(&stream->sendbuf, &ctx->stream_bufcp,
	H3_STREAM_SEND_CHUNKS, BUFQ_OPT_NONE);
	stream->sendbuf_len_in_flight = 0;
+	stream->window_size_max = H3_STREAM_WINDOW_SIZE_INITIAL;
	Curl_h1_req_parse_init(&stream->h1, H1_PARSE_DEFAULT_MAX_LINE_LEN);

	if(!Curl_uint32_hash_set(&ctx->streams, data->mid, stream)) {
@@ -470,18 +472,18 @@ static void quic_settings(struct cf_ngtcp2_ctx *ctx,
	s->initial_ts = pktx->ts;
	s->handshake_timeout = (data->set.connecttimeout > 0) ?
	data->set.connecttimeout * NGTCP2_MILLISECONDS : QUIC_HANDSHAKE_TIMEOUT;
-	s->max_window = 100 * ctx->max_stream_window;
-	s->max_stream_window = ctx->max_stream_window;
+	s->max_window = H3_CONN_WINDOW_SIZE_MAX;
+	s->max_stream_window = 0; /* disable ngtcp2 auto-tuning of window */
	s->no_pmtud = FALSE;
	#ifdef NGTCP2_SETTINGS_V3
	/* try ten times the ngtcp2 defaults here for problems with Caddy */
	s->glitch_ratelim_burst = 1000 * 10;
	s->glitch_ratelim_rate = 33 * 10;
	#endif
-	t->initial_max_data = 10 * ctx->max_stream_window;
-	t->initial_max_stream_data_bidi_local = ctx->max_stream_window;
-	t->initial_max_stream_data_bidi_remote = ctx->max_stream_window;
-	t->initial_max_stream_data_uni = ctx->max_stream_window;
+	t->initial_max_data = s->max_window;
+	t->initial_max_stream_data_bidi_local = H3_STREAM_WINDOW_SIZE_INITIAL;
+	t->initial_max_stream_data_bidi_remote = H3_STREAM_WINDOW_SIZE_INITIAL;
+	t->initial_max_stream_data_uni = t->initial_max_data;
	t->initial_max_streams_bidi = QUIC_MAX_STREAMS;
	t->initial_max_streams_uni = QUIC_MAX_STREAMS;
	t->max_idle_timeout = 0; /* no idle timeout from our side */
@@ -1047,6 +1049,28 @@ static void h3_xfer_write_resp(struct Curl_cfilter *cf,
	}
	}

+	static void cf_ngtcp2_stream_update_window(struct Curl_cfilter *cf,
+	struct Curl_easy *data,
+	struct h3_stream_ctx *stream)
+	{
+	/* stream receive max window size for flow control. We can only
+	* grow it from the initial window size */
+	uint64_t swin_max = data->progress.dl.rlimit.rate_per_step ?
+	data->progress.dl.rlimit.rate_per_step : H3_STREAM_WINDOW_SIZE_MAX;
+	if(swin_max > stream->window_size_max) {
+	struct cf_ngtcp2_ctx *ctx = cf->ctx;
+	int rc = ngtcp2_conn_extend_max_stream_offset(ctx->qconn, stream->id,
+	swin_max - stream->window_size_max);
+	if(rc) {
+	CURL_TRC_CF(data, cf, "[%" PRId64 "] extend_max_stream_offset to %"
+	PRIu64 " -> %s (%d)",
+	stream->id, swin_max, ngtcp2_strerror(rc), rc);
+	DEBUGASSERT(0);
+	}
+	stream->window_size_max = swin_max;
+	}
+	}
+
	static void cf_ngtcp2_ack_stream(struct Curl_cfilter *cf,
	struct Curl_easy *data,
	struct h3_stream_ctx *stream)
@@ -1074,6 +1098,8 @@ static void cf_ngtcp2_ack_stream(struct Curl_cfilter *cf,
	ngtcp2_conn_extend_max_stream_offset(ctx->qconn, stream->id, ack_len);
	stream->download_unacked -= ack_len;
	}
+
+	cf_ngtcp2_stream_update_window(cf, data, stream);
	}

	static int cb_h3_recv_data(nghttp3_conn *conn, int64_t stream3_id,
@@ -1635,6 +1661,8 @@ static CURLcode h3_stream_open(struct Curl_cfilter *cf,
	goto out;
	}

+	cf_ngtcp2_stream_update_window(cf, data, stream);
+
	if(Curl_trc_is_verbose(data)) {
	infof(data, "[HTTP/3] [%" PRId64 "] OPENED stream for %s",
	stream->id, Curl_bufref_ptr(&data->state.url));