Mercurial > hg > nginx
view src/os/unix/ngx_aio_read_chain.c @ 4164:c48662671609 stable-1.0
Merging r4130, r4131, r4135:
Linux AIO related fixes:
*) Fixing Linux AIO syscalls return value handling:
syscall(2) uses usual libc convention, it returns -1 on error and
sets errno. Obsolete _syscall(2) returns negative value of error.
*) Fixing Linux AIO initiatialization: AIO operations are disabled
if kernel does not support them. Previously worker just exited.
*) The "worker_aio_requests" directive.
The default value is 32 AIO simultaneous requests per worker. Previously
they were hardcoded to 1024, and it was too large, since Linux allocated
them early on io_setup(), but not on request itself. So with default value
of /proc/sys/fs/aio-max-nr equal to 65536 only 64 worker processes could
be run simultaneously. 32 AIO requests are enough for modern disks even if
server runs only 1 worker.
author | Igor Sysoev <igor@sysoev.ru> |
---|---|
date | Fri, 30 Sep 2011 14:12:53 +0000 |
parents | a1d54c705f38 |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> ssize_t ngx_aio_read_chain(ngx_connection_t *c, ngx_chain_t *cl) { int n; u_char *buf, *prev; size_t size; ssize_t total; if (c->read->pending_eof) { c->read->ready = 0; return 0; } total = 0; while (cl) { /* we can post the single aio operation only */ if (!c->read->ready) { return total ? total : NGX_AGAIN; } buf = cl->buf->last; prev = cl->buf->last; size = 0; /* coalesce the neighbouring bufs */ while (cl && prev == cl->buf->last) { size += cl->buf->end - cl->buf->last; prev = cl->buf->end; cl = cl->next; } n = ngx_aio_read(c, buf, size); ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "aio_read: %d", n); if (n == NGX_AGAIN) { return total ? total : NGX_AGAIN; } if (n == NGX_ERROR) { return NGX_ERROR; } if (n == 0) { c->read->pending_eof = 1; if (total) { c->read->eof = 0; c->read->ready = 1; } return total; } if (n > 0) { total += n; } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "aio_read total: %d", total); } return total ? total : NGX_AGAIN; }