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/cvs/libev/ev_linuxaio.c
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Comparing libev/ev_linuxaio.c (file contents):
Revision 1.7 by root, Sat Jun 22 16:25:53 2019 UTC vs.
Revision 1.9 by root, Sat Jun 22 22:29:38 2019 UTC

… …
42#include <linux/aio_abi.h> 42#include <linux/aio_abi.h>
43 43
44/* we try to fill 4kB pages exactly. 44/* we try to fill 4kB pages exactly.
45 * the ring buffer header is 32 bytes, every io event is 32 bytes. 45 * the ring buffer header is 32 bytes, every io event is 32 bytes.
46 * the kernel takes the io event number, doubles it, adds 2, adds the ring buffer. 46 * the kernel takes the io event number, doubles it, adds 2, adds the ring buffer.
47 * therefore the calculation below will use "exactly" 8kB for the ring buffer 47 * therefore the calculation below will use "exactly" 4kB for the ring buffer
48 */ 48 */
49#define EV_LINUXAIO_DEPTH (256 / 2 - 2 - 1) /* max. number of io events per batch */ 49#define EV_LINUXAIO_DEPTH (128 / 2 - 2 - 1) /* max. number of io events per batch */
50 50
51/*****************************************************************************/ 51/*****************************************************************************/
52/* syscall wrapdadoop */ 52/* syscall wrapdadoop */
53 53
54#include <sys/syscall.h> /* no glibc wrappers */ 54#include <sys/syscall.h> /* no glibc wrappers */
… …
205static int 205static int
206linuxaio_get_events_from_ring (EV_P) 206linuxaio_get_events_from_ring (EV_P)
207{ 207{
208 struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx; 208 struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx;
209 209
210 ECB_MEMORY_FENCE_ACQUIRE;
211
212 unsigned head = ring->head; 210 unsigned head = ring->head;
213 unsigned tail = *(volatile unsigned *)&ring->tail; 211 unsigned tail = *(volatile unsigned *)&ring->tail;
214 212
215 if (head == tail) 213 if (head == tail)
216 return 0; 214 return 0;
… …
219 if (ecb_expect_false (ring->magic != AIO_RING_MAGIC) 217 if (ecb_expect_false (ring->magic != AIO_RING_MAGIC)
220 || ring->incompat_features != AIO_RING_INCOMPAT_FEATURES 218 || ring->incompat_features != AIO_RING_INCOMPAT_FEATURES
221 || ring->header_length != sizeof (struct aio_ring)) /* TODO: or use it to find io_event[0]? */ 219 || ring->header_length != sizeof (struct aio_ring)) /* TODO: or use it to find io_event[0]? */
222 return 0; 220 return 0;
223 221
222 ECB_MEMORY_FENCE_ACQUIRE;
223
224 /* parse all available events, but only once, to avoid starvation */ 224 /* parse all available events, but only once, to avoid starvation */
225 if (tail > head) /* normal case around */ 225 if (tail > head) /* normal case around */
226 linuxaio_parse_events (EV_A_ ring->io_events + head, tail - head); 226 linuxaio_parse_events (EV_A_ ring->io_events + head, tail - head);
227 else /* wrapped around */ 227 else /* wrapped around */
228 { 228 {
… …
255 ts.tv_nsec = (long)((timeout - ts.tv_sec) * 1e9); 255 ts.tv_nsec = (long)((timeout - ts.tv_sec) * 1e9);
256 256
257 res = ev_io_getevents (linuxaio_ctx, 1, 1, &ioev, &ts); 257 res = ev_io_getevents (linuxaio_ctx, 1, 1, &ioev, &ts);
258 258
259 if (res < 0) 259 if (res < 0)
260 ev_syserr ("(libev) io_getevents"); 260 ev_syserr ("(libev) linuxaio io_getevents");
261 else if (res) 261 else if (res)
262 { 262 {
263 /* at least one event received, handle it and any remaining ones in the ring buffer */ 263 /* at least one event received, handle it and any remaining ones in the ring buffer */
264 linuxaio_parse_events (EV_A_ &ioev, 1); 264 linuxaio_parse_events (EV_A_ &ioev, 1);
265 linuxaio_get_events_from_ring (EV_A); 265 linuxaio_get_events_from_ring (EV_A);
… …
294 linuxaio_submitcnt -= submitted; 294 linuxaio_submitcnt -= submitted;
295 timeout = 0; 295 timeout = 0;
296 break; 296 break;
297 } 297 }
298 else 298 else
299 ev_syserr ("(libev) io_submit"); 299 ev_syserr ("(libev) linuxaio io_submit");
300 300
301 submitted += res; 301 submitted += res;
302 } 302 }
303 303
304 linuxaio_submitcnt = 0; 304 linuxaio_submitcnt = 0;
… …
350 linuxaio_destroy (EV_A); 350 linuxaio_destroy (EV_A);
351 linuxaio_submitcnt = 0; /* all pointers were invalidated */ 351 linuxaio_submitcnt = 0; /* all pointers were invalidated */
352 352
353 linuxaio_ctx = 0; 353 linuxaio_ctx = 0;
354 while (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0) 354 while (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0)
355 ev_syserr ("(libev) io_setup"); 355 ev_syserr ("(libev) linuxaio io_setup");
356 356
357 fd_rearm_all (EV_A); 357 fd_rearm_all (EV_A);
358} 358}
359 359

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