ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev_linuxaio.c
(Generate patch)

Comparing libev/ev_linuxaio.c (file contents):
Revision 1.9 by root, Sat Jun 22 22:29:38 2019 UTC vs.
Revision 1.11 by root, Sun Jun 23 22:57:25 2019 UTC

… …
35 * and other provisions required by the GPL. If you do not delete the 35 * and other provisions required by the GPL. If you do not delete the
36 * provisions above, a recipient may use your version of this file under 36 * provisions above, a recipient may use your version of this file under
37 * either the BSD or the GPL. 37 * either the BSD or the GPL.
38 */ 38 */
39 39
40#define EPOLL_FALLBACK 1
41
40#include <sys/time.h> /* actually linux/time.h, but we must assume they are compatible */ 42#include <sys/time.h> /* actually linux/time.h, but we must assume they are compatible */
41#include <poll.h> 43#include <poll.h>
42#include <linux/aio_abi.h> 44#include <linux/aio_abi.h>
45
46#if EPOLL_FALLBACK
47# include <sys/epoll.h>
48#endif
43 49
44/* we try to fill 4kB pages exactly. 50/* we try to fill 4kB pages exactly.
45 * the ring buffer header is 32 bytes, every io event is 32 bytes. 51 * 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. 52 * the kernel takes the io event number, doubles it, adds 2, adds the ring buffer.
47 * therefore the calculation below will use "exactly" 4kB for the ring buffer 53 * therefore the calculation below will use "exactly" 4kB for the ring buffer
… …
148static void 154static void
149linuxaio_modify (EV_P_ int fd, int oev, int nev) 155linuxaio_modify (EV_P_ int fd, int oev, int nev)
150{ 156{
151 array_needsize (ANIOCBP, linuxaio_iocbps, linuxaio_iocbpmax, fd + 1, linuxaio_array_needsize_iocbp); 157 array_needsize (ANIOCBP, linuxaio_iocbps, linuxaio_iocbpmax, fd + 1, linuxaio_array_needsize_iocbp);
152 struct aniocb *iocb = linuxaio_iocbps [fd]; 158 struct aniocb *iocb = linuxaio_iocbps [fd];
159
160#if EPOLL_FALLBACK
161 if (iocb->io.aio_reqprio < 0)
162 {
163 epoll_ctl (backend_fd, EPOLL_CTL_DEL, fd, 0);
164 iocb->io.aio_reqprio = 0;
165 }
166#endif
153 167
154 if (iocb->io.aio_buf) 168 if (iocb->io.aio_buf)
155 ev_io_cancel (linuxaio_ctx, &iocb->io, (struct io_event *)0); /* always returns an error relevant kernels */ 169 ev_io_cancel (linuxaio_ctx, &iocb->io, (struct io_event *)0); /* always returns an error relevant kernels */
156 170
157 if (nev) 171 if (nev)
… …
228 { 242 {
229 linuxaio_parse_events (EV_A_ ring->io_events + head, ring->nr - head); 243 linuxaio_parse_events (EV_A_ ring->io_events + head, ring->nr - head);
230 linuxaio_parse_events (EV_A_ ring->io_events, tail); 244 linuxaio_parse_events (EV_A_ ring->io_events, tail);
231 } 245 }
232 246
233 ring->head = tail; 247 *(volatile unsigned *)&ring->head = tail;
248
249 /* again, other implementations don't do this, but I think it's required for the kernel to see free slots */
250 ECB_MEMORY_FENCE_RELEASE;
234 251
235 return 1; 252 return 1;
236} 253}
237 254
238/* read at least one event from kernel, or timeout */ 255/* read at least one event from kernel, or timeout */
… …
255 ts.tv_nsec = (long)((timeout - ts.tv_sec) * 1e9); 272 ts.tv_nsec = (long)((timeout - ts.tv_sec) * 1e9);
256 273
257 res = ev_io_getevents (linuxaio_ctx, 1, 1, &ioev, &ts); 274 res = ev_io_getevents (linuxaio_ctx, 1, 1, &ioev, &ts);
258 275
259 if (res < 0) 276 if (res < 0)
277 if (errno == EINTR)
278 /* ignored */;
279 else
260 ev_syserr ("(libev) linuxaio io_getevents"); 280 ev_syserr ("(libev) linuxaio io_getevents");
261 else if (res) 281 else if (res)
262 { 282 {
263 /* at least one event received, handle it and any remaining ones in the ring buffer */ 283 /* at least one event received, handle it and any remaining ones in the ring buffer */
264 linuxaio_parse_events (EV_A_ &ioev, 1); 284 linuxaio_parse_events (EV_A_ &ioev, 1);
265 linuxaio_get_events_from_ring (EV_A); 285 linuxaio_get_events_from_ring (EV_A);
266 } 286 }
267} 287}
288
289#if EPOLL_FALLBACK
290static void
291linuxaio_rearm_epoll (EV_P_ struct iocb *iocb, int op)
292{
293 struct epoll_event eev;
294
295 eev.events = EPOLLONESHOT;
296 if (iocb->aio_buf & POLLIN ) eev.events |= EPOLLIN ;
297 if (iocb->aio_buf & POLLOUT) eev.events |= EPOLLOUT;
298 eev.data.fd = iocb->aio_fildes;
299
300 if (epoll_ctl (backend_fd, op, iocb->aio_fildes, &eev) < 0)
301 ev_syserr ("(libeio) linuxaio epoll_ctl");
302}
303#endif
268 304
269static void 305static void
270linuxaio_poll (EV_P_ ev_tstamp timeout) 306linuxaio_poll (EV_P_ ev_tstamp timeout)
271{ 307{
272 int submitted; 308 int submitted;
… …
283 if (ecb_expect_false (res < 0)) 319 if (ecb_expect_false (res < 0))
284 if (errno == EAGAIN) 320 if (errno == EAGAIN)
285 { 321 {
286 /* This happens when the ring buffer is full, at least. I assume this means 322 /* This happens when the ring buffer is full, at least. I assume this means
287 * that the event was queued synchronously during io_submit, and thus 323 * that the event was queued synchronously during io_submit, and thus
288 * the buffer overflowd. 324 * the buffer overflowed.
289 * In this case, we just try next loop iteration. 325 * In this case, we just try in next loop iteration.
290 * This should not result in a few fds taking priority, as the interface 326 * This should not result in a few fds taking priority, as the interface
291 * is one-shot, and we submit iocb's in a round-robin fashion. 327 * is one-shot, and we submit iocb's in a round-robin fashion.
292 */ 328 */
293 memmove (linuxaio_submits, linuxaio_submits + submitted, (linuxaio_submitcnt - submitted) * sizeof (*linuxaio_submits)); 329 memmove (linuxaio_submits, linuxaio_submits + submitted, (linuxaio_submitcnt - submitted) * sizeof (*linuxaio_submits));
294 linuxaio_submitcnt -= submitted; 330 linuxaio_submitcnt -= submitted;
295 timeout = 0; 331 timeout = 0;
296 break; 332 break;
297 } 333 }
334#if EPOLL_FALLBACK
335 else if (errno == EINVAL)
336 {
337 /* This hapüpens for unsupported fds, officially, but in my testing,
338 * also randomly happens for supported fds. We fall back to good old
339 * poll() here, under the assumption that this is a very rare case.
340 */
341 struct iocb *iocb = linuxaio_submits [submitted];
342 res = 1; /* skip this iocb */
343
344 linuxaio_rearm_epoll (EV_A_ iocb, EPOLL_CTL_ADD);
345 iocb->aio_reqprio = -1; /* mark iocb as epoll */
346 }
347#endif
298 else 348 else
299 ev_syserr ("(libev) linuxaio io_submit"); 349 ev_syserr ("(libev) linuxaio io_submit");
300 350
301 submitted += res; 351 submitted += res;
302 } 352 }
… …
305 355
306 /* second phase: fetch and parse events */ 356 /* second phase: fetch and parse events */
307 357
308 linuxaio_get_events (EV_A_ timeout); 358 linuxaio_get_events (EV_A_ timeout);
309} 359}
360
361#if EPOLL_FALLBACK
362
363static void
364linuxaio_epoll_cb (EV_P_ struct ev_io *w, int revents)
365{
366 struct epoll_event events[16];
367
368 for (;;)
369 {
370 int idx;
371 int res = epoll_wait (backend_fd, events, sizeof (events) / sizeof (events [0]), 0);
372
373 if (ecb_expect_false (res < 0))
374 ev_syserr ("(libev) linuxaio epoll_wait");
375 else if (!res)
376 break;
377
378 for (idx = res; idx--; )
379 {
380 int fd = events [idx].data.fd;
381 uint32_t ev = events [idx].events;
382
383 assert (("libev: iocb fd must be in-bounds", fd >= 0 && fd < anfdmax));
384
385 linuxaio_rearm_epoll (EV_A_ &linuxaio_iocbps [fd]->io, EPOLL_CTL_MOD);
386
387 fd_event (EV_A_ fd,
388 (ev & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
389 | (ev & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0));
390 }
391
392 if (res < sizeof (events) / sizeof (events [0]))
393 break;
394 }
395}
396
397#endif
310 398
311inline_size 399inline_size
312int 400int
313linuxaio_init (EV_P_ int flags) 401linuxaio_init (EV_P_ int flags)
314{ 402{
… …
319 407
320 linuxaio_ctx = 0; 408 linuxaio_ctx = 0;
321 if (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0) 409 if (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0)
322 return 0; 410 return 0;
323 411
412#if EPOLL_FALLBACK
413 backend_fd = ev_epoll_create ();
414 if (backend_fd < 0)
415 {
416 ev_io_destroy (linuxaio_ctx);
417 return 0;
418 }
419
420 ev_io_init (EV_A_ &linuxaio_epoll_w, linuxaio_epoll_cb, backend_fd, EV_READ);
421 ev_io_start (EV_A_ &linuxaio_epoll_w);
422#endif
423
324 backend_modify = linuxaio_modify; 424 backend_modify = linuxaio_modify;
325 backend_poll = linuxaio_poll; 425 backend_poll = linuxaio_poll;
326 426
327 linuxaio_iocbpmax = 0; 427 linuxaio_iocbpmax = 0;
328 linuxaio_iocbps = 0; 428 linuxaio_iocbps = 0;
… …
336 436
337inline_size 437inline_size
338void 438void
339linuxaio_destroy (EV_P) 439linuxaio_destroy (EV_P)
340{ 440{
441#if EPOLL_FALLBACK
442 close (backend_fd);
443#endif
341 linuxaio_free_iocbp (EV_A); 444 linuxaio_free_iocbp (EV_A);
342 ev_io_destroy (linuxaio_ctx); 445 ev_io_destroy (linuxaio_ctx);
343} 446}
344 447
345inline_size 448inline_size
… …
352 455
353 linuxaio_ctx = 0; 456 linuxaio_ctx = 0;
354 while (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0) 457 while (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0)
355 ev_syserr ("(libev) linuxaio io_setup"); 458 ev_syserr ("(libev) linuxaio io_setup");
356 459
460#if EPOLL_FALLBACK
461 while ((backend_fd = ev_epoll_create ()) < 0)
462 ev_syserr ("(libev) linuxaio epoll_create");
463
464 ev_io_stop (EV_A_ &linuxaio_epoll_w);
465 ev_io_init (EV_A_ &linuxaio_epoll_w, linuxaio_epoll_cb, backend_fd, EV_READ);
466 ev_io_start (EV_A_ &linuxaio_epoll_w);
467 ev_unref (EV_A); /* watcher should not keep loop alive */
468#endif
469
357 fd_rearm_all (EV_A); 470 fd_rearm_all (EV_A);
358} 471}
359 472

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines