Mercurial > hg > nginx-quic
view src/core/ngx_cpuinfo.c @ 9067:f68fdb017141 quic
QUIC: optimized sending stream response.
When a stream is created by client, it's often the case that nginx will send
immediate response on that stream. An example is HTTP/3 request stream, which
in most cases quickly replies with at least HTTP headers.
QUIC stream init handlers are called from a posted event. Output QUIC
frames are also sent to client from a posted event, called the push event.
If the push event is posted before the stream init event, then output produced
by stream may trigger sending an extra UDP datagram. To address this, push
event is now re-posted when a new stream init event is posted.
An example is handling 0-RTT packets. Client typically sends an init packet
coalesced with a 0-RTT packet. Previously, nginx replied with a padded CRYPTO
datagram, followed by a 1-RTT stream reply datagram. Now CRYPTO and STREAM
packets are coalesced in one reply datagram, which saves bandwidth.
Other examples include coalescing 1-RTT first stream response, and
MAX_STREAMS/STREAM sent in response to ACK/STREAM.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Mon, 03 Apr 2023 16:17:12 +0400 |
parents | d620f497c50f |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #if (( __i386__ || __amd64__ ) && ( __GNUC__ || __INTEL_COMPILER )) static ngx_inline void ngx_cpuid(uint32_t i, uint32_t *buf); #if ( __i386__ ) static ngx_inline void ngx_cpuid(uint32_t i, uint32_t *buf) { /* * we could not use %ebx as output parameter if gcc builds PIC, * and we could not save %ebx on stack, because %esp is used, * when the -fomit-frame-pointer optimization is specified. */ __asm__ ( " mov %%ebx, %%esi; " " cpuid; " " mov %%eax, (%1); " " mov %%ebx, 4(%1); " " mov %%edx, 8(%1); " " mov %%ecx, 12(%1); " " mov %%esi, %%ebx; " : : "a" (i), "D" (buf) : "ecx", "edx", "esi", "memory" ); } #else /* __amd64__ */ static ngx_inline void ngx_cpuid(uint32_t i, uint32_t *buf) { uint32_t eax, ebx, ecx, edx; __asm__ ( "cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" (i) ); buf[0] = eax; buf[1] = ebx; buf[2] = edx; buf[3] = ecx; } #endif /* auto detect the L2 cache line size of modern and widespread CPUs */ void ngx_cpuinfo(void) { u_char *vendor; uint32_t vbuf[5], cpu[4], model; vbuf[0] = 0; vbuf[1] = 0; vbuf[2] = 0; vbuf[3] = 0; vbuf[4] = 0; ngx_cpuid(0, vbuf); vendor = (u_char *) &vbuf[1]; if (vbuf[0] == 0) { return; } ngx_cpuid(1, cpu); if (ngx_strcmp(vendor, "GenuineIntel") == 0) { switch ((cpu[0] & 0xf00) >> 8) { /* Pentium */ case 5: ngx_cacheline_size = 32; break; /* Pentium Pro, II, III */ case 6: ngx_cacheline_size = 32; model = ((cpu[0] & 0xf0000) >> 8) | (cpu[0] & 0xf0); if (model >= 0xd0) { /* Intel Core, Core 2, Atom */ ngx_cacheline_size = 64; } break; /* * Pentium 4, although its cache line size is 64 bytes, * it prefetches up to two cache lines during memory read */ case 15: ngx_cacheline_size = 128; break; } } else if (ngx_strcmp(vendor, "AuthenticAMD") == 0) { ngx_cacheline_size = 64; } } #else void ngx_cpuinfo(void) { } #endif