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Simplified sendfile(SF_NODISKIO) usage.

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Starting with FreeBSD 11, there is no need to use AIO operations to preload
data into cache for sendfile(SF_NODISKIO) to work.  Instead, sendfile()
handles non-blocking loading data from disk by itself.  It still can, however,
return EBUSY if a page is already being loaded (for example, by a different
process).  If this happens, we now post an event for the next event loop
iteration, so sendfile() is retried "after a short period", as manpage
recommends.

The limit of the number of EBUSY tolerated without any progress is preserved,
but now it does not result in an alert, since on an idle system event loop
iteration might be very short and EBUSY can happen many times in a row.
Instead, SF_NODISKIO is simply disabled for one call once the limit is
reached.

With this change, sendfile(SF_NODISKIO) is now used automatically as long as
sendfile() is enabled, and no longer requires "aio on;".
This commit is contained in:
Maxim Dounin 2021-12-27 19:48:33 +03:00
parent f0a5ce136d
commit 20c35434ef
8 changed files with 33 additions and 174 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
auto/os/freebsd
View File

@ -44,12 +44,10 @@ if [ $osreldate -gt 300007 ]; then
CORE_SRCS="$CORE_SRCS $FREEBSD_SENDFILE_SRCS"
fi
if [ $NGX_FILE_AIO = YES ]; then
if [ $osreldate -gt 502103 ]; then
if [ $osreldate -gt 1100093 ]; then
echo " + sendfile()'s SF_NODISKIO found"
have=NGX_HAVE_AIO_SENDFILE . auto/have
fi
have=NGX_HAVE_SENDFILE_NODISKIO . auto/have
fi
# POSIX semaphores

3
src/core/ngx_buf.h
View File

@ -90,9 +90,6 @@ struct ngx_output_chain_ctx_s {
#if (NGX_HAVE_FILE_AIO || NGX_COMPAT)
ngx_output_chain_aio_pt aio_handler;
#if (NGX_HAVE_AIO_SENDFILE || NGX_COMPAT)
ssize_t (*aio_preload)(ngx_buf_t *file);
#endif
#endif
#if (NGX_THREADS || NGX_COMPAT)

2
src/core/ngx_connection.h
View File

@ -185,7 +185,7 @@ struct ngx_connection_s {
unsigned need_last_buf:1;
#if (NGX_HAVE_AIO_SENDFILE || NGX_COMPAT)
#if (NGX_HAVE_SENDFILE_NODISKIO || NGX_COMPAT)
unsigned busy_count:2;
#endif

2
src/core/ngx_module.h
View File

@ -41,7 +41,7 @@
#define NGX_MODULE_SIGNATURE_3 "0"
#endif
#if (NGX_HAVE_AIO_SENDFILE || NGX_COMPAT)
#if (NGX_HAVE_SENDFILE_NODISKIO || NGX_COMPAT)
#define NGX_MODULE_SIGNATURE_4 "1"
#else
#define NGX_MODULE_SIGNATURE_4 "0"

32
src/core/ngx_output_chain.c
View File

@ -29,10 +29,6 @@
static ngx_inline ngx_int_t
ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf);
#if (NGX_HAVE_AIO_SENDFILE)
static ngx_int_t ngx_output_chain_aio_setup(ngx_output_chain_ctx_t *ctx,
ngx_file_t *file);
#endif
static ngx_int_t ngx_output_chain_add_copy(ngx_pool_t *pool,
ngx_chain_t **chain, ngx_chain_t *in);
static ngx_int_t ngx_output_chain_align_file_buf(ngx_output_chain_ctx_t *ctx,
@ -283,12 +279,6 @@ ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf)
buf->in_file = 0;
}
#if (NGX_HAVE_AIO_SENDFILE)
if (ctx->aio_preload && buf->in_file) {
(void) ngx_output_chain_aio_setup(ctx, buf->file);
}
#endif
if (ctx->need_in_memory && !ngx_buf_in_memory(buf)) {
return 0;
}
@ -301,28 +291,6 @@ ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf)
}
#if (NGX_HAVE_AIO_SENDFILE)
static ngx_int_t
ngx_output_chain_aio_setup(ngx_output_chain_ctx_t *ctx, ngx_file_t *file)
{
ngx_event_aio_t *aio;
if (file->aio == NULL && ngx_file_aio_init(file, ctx->pool) != NGX_OK) {
return NGX_ERROR;
}
aio = file->aio;
aio->data = ctx->filter_ctx;
aio->preload_handler = ctx->aio_preload;
return NGX_OK;
}
#endif
static ngx_int_t
ngx_output_chain_add_copy(ngx_pool_t *pool, ngx_chain_t **chain,
ngx_chain_t *in)

4
src/event/ngx_event.h
View File

@ -147,10 +147,6 @@ struct ngx_event_aio_s {
ngx_fd_t fd;
#if (NGX_HAVE_AIO_SENDFILE || NGX_COMPAT)
ssize_t (*preload_handler)(ngx_buf_t *file);
#endif
#if (NGX_HAVE_EVENTFD)
int64_t res;
#endif

82
src/http/ngx_http_copy_filter_module.c
View File

@ -19,10 +19,6 @@ typedef struct {
static void ngx_http_copy_aio_handler(ngx_output_chain_ctx_t *ctx,
ngx_file_t *file);
static void ngx_http_copy_aio_event_handler(ngx_event_t *ev);
#if (NGX_HAVE_AIO_SENDFILE)
static ssize_t ngx_http_copy_aio_sendfile_preload(ngx_buf_t *file);
static void ngx_http_copy_aio_sendfile_event_handler(ngx_event_t *ev);
#endif
#endif
#if (NGX_THREADS)
static ngx_int_t ngx_http_copy_thread_handler(ngx_thread_task_t *task,
@ -128,9 +124,6 @@ ngx_http_copy_filter(ngx_http_request_t *r, ngx_chain_t *in)
#if (NGX_HAVE_FILE_AIO)
if (ngx_file_aio && clcf->aio == NGX_HTTP_AIO_ON) {
ctx->aio_handler = ngx_http_copy_aio_handler;
#if (NGX_HAVE_AIO_SENDFILE)
ctx->aio_preload = ngx_http_copy_aio_sendfile_preload;
#endif
}
#endif
@ -207,81 +200,6 @@ ngx_http_copy_aio_event_handler(ngx_event_t *ev)
ngx_http_run_posted_requests(c);
}
#if (NGX_HAVE_AIO_SENDFILE)
static ssize_t
ngx_http_copy_aio_sendfile_preload(ngx_buf_t *file)
{
ssize_t n;
static u_char buf[1];
ngx_event_aio_t *aio;
ngx_http_request_t *r;
ngx_output_chain_ctx_t *ctx;
aio = file->file->aio;
r = aio->data;
if (r->aio) {
/*
* tolerate sendfile() calls if another operation is already
* running; this can happen due to subrequests, multiple calls
* of the next body filter from a filter, or in HTTP/2 due to
* a write event on the main connection
*/
return NGX_AGAIN;
}
n = ngx_file_aio_read(file->file, buf, 1, file->file_pos, NULL);
if (n == NGX_AGAIN) {
aio->handler = ngx_http_copy_aio_sendfile_event_handler;
r->main->blocked++;
r->aio = 1;
ctx = ngx_http_get_module_ctx(r, ngx_http_copy_filter_module);
ctx->aio = 1;
}
return n;
}
static void
ngx_http_copy_aio_sendfile_event_handler(ngx_event_t *ev)
{
ngx_event_aio_t *aio;
ngx_connection_t *c;
ngx_http_request_t *r;
aio = ev->data;
r = aio->data;
c = r->connection;
r->main->blocked--;
r->aio = 0;
ev->complete = 0;
#if (NGX_HTTP_V2)
if (r->stream) {
/*
* for HTTP/2, update write event to make sure processing will
* reach the main connection to handle sendfile() preload
*/
c->write->ready = 1;
c->write->active = 0;
}
#endif
c->write->handler(c->write);
}
#endif
#endif

50
src/os/unix/ngx_freebsd_sendfile_chain.c
View File

@ -36,19 +36,18 @@ ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
off_t send, prev_send, sent;
size_t file_size;
ssize_t n;
ngx_uint_t eintr, eagain;
ngx_err_t err;
ngx_buf_t *file;
ngx_uint_t eintr, eagain;
#if (NGX_HAVE_SENDFILE_NODISKIO)
ngx_uint_t ebusy;
#endif
ngx_event_t *wev;
ngx_chain_t *cl;
ngx_iovec_t header, trailer;
struct sf_hdtr hdtr;
struct iovec headers[NGX_IOVS_PREALLOCATE];
struct iovec trailers[NGX_IOVS_PREALLOCATE];
#if (NGX_HAVE_AIO_SENDFILE)
ngx_uint_t ebusy;
ngx_event_aio_t *aio;
#endif
wev = c->write;
@ -77,11 +76,6 @@ ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
eagain = 0;
flags = 0;
#if (NGX_HAVE_AIO_SENDFILE && NGX_SUPPRESS_WARN)
aio = NULL;
file = NULL;
#endif
header.iovs = headers;
header.nalloc = NGX_IOVS_PREALLOCATE;
@ -90,7 +84,7 @@ ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
for ( ;; ) {
eintr = 0;
#if (NGX_HAVE_AIO_SENDFILE)
#if (NGX_HAVE_SENDFILE_NODISKIO)
ebusy = 0;
#endif
prev_send = send;
@ -179,9 +173,8 @@ ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
sent = 0;
#if (NGX_HAVE_AIO_SENDFILE)
aio = file->file->aio;
flags = (aio && aio->preload_handler) ? SF_NODISKIO : 0;
#if (NGX_HAVE_SENDFILE_NODISKIO)
flags = (c->busy_count <= 2) ? SF_NODISKIO : 0;
#endif
rc = sendfile(file->file->fd, c->fd, file->file_pos,
@ -199,7 +192,7 @@ ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
eintr = 1;
break;
#if (NGX_HAVE_AIO_SENDFILE)
#if (NGX_HAVE_SENDFILE_NODISKIO)
case NGX_EBUSY:
ebusy = 1;
break;
@ -252,41 +245,30 @@ ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
in = ngx_chain_update_sent(in, sent);
#if (NGX_HAVE_AIO_SENDFILE)
#if (NGX_HAVE_SENDFILE_NODISKIO)
if (ebusy) {
if (sent == 0) {
c->busy_count++;
if (c->busy_count > 2) {
ngx_log_error(NGX_LOG_ALERT, c->log, 0,
"sendfile(%V) returned busy again",
&file->file->name);
c->busy_count = 0;
aio->preload_handler = NULL;
send = prev_send;
continue;
}
ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
"sendfile() busy, count:%d", c->busy_count);
} else {
c->busy_count = 0;
}
n = aio->preload_handler(file);
if (n > 0) {
send = prev_send + sent;
continue;
if (wev->posted) {
ngx_delete_posted_event(wev);
}
ngx_post_event(wev, &ngx_posted_next_events);
wev->ready = 0;
return in;
}
if (flags == SF_NODISKIO) {
c->busy_count = 0;
}
#endif