Mercurial > hg > nginx-quic
view src/core/ngx_spinlock.c @ 4434:80df7b82d3c9 stable-1.0
Merge r4336:
Microoptimization of sendfile(2) usage under FreeBSD.
FreeBSD kernel checks headers/trailers pointer against NULL, not
corresponding count. Passing NULL if there are no headers/trailers
helps to avoid unneeded work in kernel, as well as unexpected 0 bytes
GIO in traces.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Sun, 05 Feb 2012 12:42:36 +0000 |
parents | 3f8a2132b93d |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> void ngx_spinlock(ngx_atomic_t *lock, ngx_atomic_int_t value, ngx_uint_t spin) { #if (NGX_HAVE_ATOMIC_OPS) ngx_uint_t i, n; for ( ;; ) { if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) { return; } if (ngx_ncpu > 1) { for (n = 1; n < spin; n <<= 1) { for (i = 0; i < n; i++) { ngx_cpu_pause(); } if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) { return; } } } ngx_sched_yield(); } #else #if (NGX_THREADS) #error ngx_spinlock() or ngx_atomic_cmp_set() are not defined ! #endif #endif }