Mercurial > hg > nginx
comparison src/event/quic/ngx_event_quic_ack.c @ 9138:a90f79792b5d
QUIC: optimized ACK delay.
Previously ACK was not generated if max_ack_delay was not yet expired and the
number of unacknowledged ack-eliciting packets was less than two, as allowed by
RFC 9000 13.2.1-13.2.2. However this only makes sense to avoid sending ACK-only
packets, as explained by the RFC:
On the other hand, reducing the frequency of packets that carry only
acknowledgments reduces packet transmission and processing cost at both
endpoints.
Now ACK is delayed only if output frame queue is empty. Otherwise ACK is sent
immediately, which significantly improves QUIC performance with certain tests.
author | Roman Arutyunyan <arut@nginx.com> |
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date | Thu, 27 Jul 2023 16:37:17 +0400 |
parents | a32905d6fc10 |
children | 5d1e7c74aadf |
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9137:0ba26c99b3a1 | 9138:a90f79792b5d |
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1169 if (ctx->level == ssl_encryption_application) { | 1169 if (ctx->level == ssl_encryption_application) { |
1170 | 1170 |
1171 delay = ngx_current_msec - ctx->ack_delay_start; | 1171 delay = ngx_current_msec - ctx->ack_delay_start; |
1172 qc = ngx_quic_get_connection(c); | 1172 qc = ngx_quic_get_connection(c); |
1173 | 1173 |
1174 if (ctx->send_ack < NGX_QUIC_MAX_ACK_GAP | 1174 if (ngx_queue_empty(&ctx->frames) |
1175 && ctx->send_ack < NGX_QUIC_MAX_ACK_GAP | |
1175 && delay < qc->tp.max_ack_delay) | 1176 && delay < qc->tp.max_ack_delay) |
1176 { | 1177 { |
1177 if (!qc->push.timer_set && !qc->closing) { | 1178 if (!qc->push.timer_set && !qc->closing) { |
1178 ngx_add_timer(&qc->push, | 1179 ngx_add_timer(&qc->push, |
1179 qc->tp.max_ack_delay - delay); | 1180 qc->tp.max_ack_delay - delay); |