Marc Alexander Lehmann
2 years ago
10 changed files with 493 additions and 82 deletions
-
3Changes
-
80ev.3
-
96ev.c
-
19ev.h
-
4ev_epoll.c
-
4ev_kqueue.c
-
342ev_linuxaio.c
-
4ev_poll.c
-
11ev_vars.h
-
12ev_wrap.h
@ -0,0 +1,342 @@ |
|||
/* |
|||
* libev linux aio fd activity backend |
|||
* |
|||
* Copyright (c) 2019 Marc Alexander Lehmann <libev@schmorp.de> |
|||
* All rights reserved. |
|||
* |
|||
* Redistribution and use in source and binary forms, with or without modifica- |
|||
* tion, are permitted provided that the following conditions are met: |
|||
* |
|||
* 1. Redistributions of source code must retain the above copyright notice, |
|||
* this list of conditions and the following disclaimer. |
|||
* |
|||
* 2. Redistributions in binary form must reproduce the above copyright |
|||
* notice, this list of conditions and the following disclaimer in the |
|||
* documentation and/or other materials provided with the distribution. |
|||
* |
|||
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
|||
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- |
|||
* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
|||
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- |
|||
* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
|||
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
|||
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
|||
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- |
|||
* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
|||
* OF THE POSSIBILITY OF SUCH DAMAGE. |
|||
* |
|||
* Alternatively, the contents of this file may be used under the terms of |
|||
* the GNU General Public License ("GPL") version 2 or any later version, |
|||
* in which case the provisions of the GPL are applicable instead of |
|||
* the above. If you wish to allow the use of your version of this file |
|||
* only under the terms of the GPL and not to allow others to use your |
|||
* version of this file under the BSD license, indicate your decision |
|||
* by deleting the provisions above and replace them with the notice |
|||
* and other provisions required by the GPL. If you do not delete the |
|||
* provisions above, a recipient may use your version of this file under |
|||
* either the BSD or the GPL. |
|||
*/ |
|||
|
|||
#include <sys/time.h> /* actually linux/time.h, but we must assume they are compatible */ |
|||
#include <linux/aio_abi.h> |
|||
|
|||
/* we try to fill 4kn pages exactly. |
|||
* the ring buffer header is 32 bytes, every io event is 32 bytes. |
|||
* the kernel takes the io event number, doubles it, adds 2, adds the ring buffer |
|||
* so the calculation below will use "exactly" 8kB for the ring buffer |
|||
*/ |
|||
#define EV_LINUXAIO_DEPTH (256 / 2 - 2 - 1) /* max. number of io events per batch */ |
|||
|
|||
/*****************************************************************************/ |
|||
/* syscall wrapdadoop */ |
|||
|
|||
#include <sys/syscall.h> /* no glibc wrappers */ |
|||
|
|||
/* aio_abi.h is not verioned in any way, so we cannot test for its existance */ |
|||
#define IOCB_CMD_POLL 5 |
|||
|
|||
/* taken from linux/fs/aio.c */ |
|||
#define AIO_RING_MAGIC 0xa10a10a1 |
|||
#define AIO_RING_INCOMPAT_FEATURES 0 |
|||
struct aio_ring |
|||
{ |
|||
unsigned id; /* kernel internal index number */ |
|||
unsigned nr; /* number of io_events */ |
|||
unsigned head; /* Written to by userland or by kernel. */ |
|||
unsigned tail; |
|||
|
|||
unsigned magic; |
|||
unsigned compat_features; |
|||
unsigned incompat_features; |
|||
unsigned header_length; /* size of aio_ring */ |
|||
|
|||
struct io_event io_events[0]; |
|||
}; |
|||
|
|||
static int |
|||
ev_io_setup (unsigned nr_events, aio_context_t *ctx_idp) |
|||
{ |
|||
return syscall (SYS_io_setup, nr_events, ctx_idp); |
|||
} |
|||
|
|||
static int |
|||
ev_io_destroy (aio_context_t ctx_id) |
|||
{ |
|||
return syscall (SYS_io_destroy, ctx_id); |
|||
} |
|||
|
|||
static int |
|||
ev_io_submit (aio_context_t ctx_id, long nr, struct iocb *cbp[]) |
|||
{ |
|||
return syscall (SYS_io_submit, ctx_id, nr, cbp); |
|||
} |
|||
|
|||
static int |
|||
ev_io_cancel (aio_context_t ctx_id, struct iocb *cbp, struct io_event *result) |
|||
{ |
|||
return syscall (SYS_io_cancel, ctx_id, cbp, result); |
|||
} |
|||
|
|||
static int |
|||
ev_io_getevents (aio_context_t ctx_id, long min_nr, long nr, struct io_event *events, struct timespec *timeout) |
|||
{ |
|||
return syscall (SYS_io_getevents, ctx_id, min_nr, nr, events, timeout); |
|||
} |
|||
|
|||
typedef void (*ev_io_cb) (long nr, struct io_event *events); |
|||
|
|||
/*****************************************************************************/ |
|||
/* actual backed implementation */ |
|||
|
|||
/* two iocbs for every fd, one for read, one for write */ |
|||
typedef struct aniocb |
|||
{ |
|||
struct iocb io; |
|||
/*int inuse;*/ |
|||
} *ANIOCBP; |
|||
|
|||
inline_size |
|||
void |
|||
linuxaio_array_needsize_iocbp (ANIOCBP *base, int count) |
|||
{ |
|||
/* TODO: quite the overhead to allocate every iocb separately */ |
|||
while (count--) |
|||
{ |
|||
*base = (ANIOCBP)ev_malloc (sizeof (**base)); |
|||
memset (*base, 0, sizeof (**base)); |
|||
/* would be nice to initialize fd/data as well */ |
|||
(*base)->io.aio_lio_opcode = IOCB_CMD_POLL; |
|||
++base; |
|||
} |
|||
} |
|||
|
|||
static void |
|||
linuxaio_free_iocbp (EV_P) |
|||
{ |
|||
while (linuxaio_iocbpmax--) |
|||
ev_free (linuxaio_iocbps [linuxaio_iocbpmax]); |
|||
|
|||
linuxaio_iocbpmax = 0; |
|||
} |
|||
|
|||
static void |
|||
linuxaio_modify (EV_P_ int fd, int oev, int nev) |
|||
{ |
|||
/* TODO: full zero initialize required? */ |
|||
array_needsize (ANIOCBP, linuxaio_iocbps, linuxaio_iocbpmax, fd + 1, linuxaio_array_needsize_iocbp); |
|||
struct aniocb *iocb = linuxaio_iocbps [fd]; |
|||
|
|||
if (iocb->io.aio_buf) |
|||
ev_io_cancel (linuxaio_ctx, &iocb->io, (void *)0); |
|||
|
|||
if (nev) |
|||
{ |
|||
iocb->io.aio_data = fd; |
|||
iocb->io.aio_fildes = fd; |
|||
iocb->io.aio_buf = |
|||
(nev & EV_READ ? POLLIN : 0) |
|||
| (nev & EV_WRITE ? POLLOUT : 0); |
|||
|
|||
/* queue iocb up for io_submit */ |
|||
/* this assumes we only ever get one call per fd per loop iteration */ |
|||
++linuxaio_submitcnt; |
|||
array_needsize (struct iocb *, linuxaio_submits, linuxaio_submitmax, linuxaio_submitcnt, array_needsize_noinit); |
|||
linuxaio_submits [linuxaio_submitcnt - 1] = &iocb->io; |
|||
} |
|||
} |
|||
|
|||
static void |
|||
linuxaio_parse_events (EV_P_ struct io_event *ev, int nr) |
|||
{ |
|||
while (nr) |
|||
{ |
|||
int fd = ev->data; |
|||
int res = ev->res; |
|||
|
|||
assert (("libev: iocb fd must be in-bounds", fd >= 0 && fd < anfdxmax)); |
|||
|
|||
/* linux aio is oneshot: rearm fd */ |
|||
linuxaio_iocbps [fd]->io.aio_buf = 0; |
|||
anfds [fd].events = 0; |
|||
fd_change (EV_A_ fd, 0); |
|||
|
|||
/* feed events, we do not expect or handle POLLNVAL */ |
|||
if (ecb_expect_false (res & POLLNVAL)) |
|||
fd_kill (EV_A_ fd); |
|||
else |
|||
fd_event ( |
|||
EV_A_ |
|||
fd, |
|||
(res & (POLLOUT | POLLERR | POLLHUP) ? EV_WRITE : 0) |
|||
| (res & (POLLIN | POLLERR | POLLHUP) ? EV_READ : 0) |
|||
); |
|||
|
|||
--nr; |
|||
++ev; |
|||
} |
|||
} |
|||
|
|||
/* get any events from ringbuffer, return true if any were handled */ |
|||
static int |
|||
linuxaio_get_events_from_ring (EV_P) |
|||
{ |
|||
struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx; |
|||
|
|||
ECB_MEMORY_FENCE_ACQUIRE; |
|||
|
|||
unsigned head = ring->head; |
|||
unsigned tail = *(volatile unsigned *)&ring->tail; |
|||
|
|||
if (ring->magic != AIO_RING_MAGIC |
|||
|| ring->incompat_features != AIO_RING_INCOMPAT_FEATURES |
|||
|| ring->header_length != sizeof (struct aio_ring) /* TODO: or use it to find io_event[0]? */ |
|||
|| head == tail) |
|||
return 0; |
|||
|
|||
/* parse all available events, but only once, to avoid starvation */ |
|||
if (tail > head) /* normal case around */ |
|||
linuxaio_parse_events (EV_A_ ring->io_events + head, tail - head); |
|||
else |
|||
{ |
|||
/* wrapped around */ |
|||
linuxaio_parse_events (EV_A_ ring->io_events + head, ring->nr - head); |
|||
linuxaio_parse_events (EV_A_ ring->io_events, tail); |
|||
} |
|||
|
|||
ring->head = tail; |
|||
|
|||
return 1; |
|||
} |
|||
|
|||
/* read at least one event from kernel, or timeout */ |
|||
inline_size |
|||
void |
|||
linuxaio_get_events (EV_P_ ev_tstamp timeout) |
|||
{ |
|||
struct timespec ts; |
|||
struct io_event ioev; |
|||
int res; |
|||
|
|||
if (linuxaio_get_events_from_ring (EV_A)) |
|||
return; |
|||
|
|||
/* no events, so wait for at least one, then poll ring buffer again */ |
|||
/* this degraded to one event per loop iteration */ |
|||
/* if the ring buffer changes layout, but so be it */ |
|||
|
|||
ts.tv_sec = (long)timeout; |
|||
ts.tv_nsec = (long)((timeout - ts.tv_sec) * 1e9); |
|||
|
|||
res = ev_io_getevents (linuxaio_ctx, 1, 1, &ioev, &ts); |
|||
|
|||
if (res < 0) |
|||
ev_syserr ("(libev) io_getevents"); |
|||
else if (res) |
|||
{ |
|||
/* at least one event received, handle it and any remaining ones in the ring buffer */ |
|||
linuxaio_parse_events (EV_A_ &ioev, 1); |
|||
linuxaio_get_events_from_ring (EV_A); |
|||
} |
|||
} |
|||
|
|||
static void |
|||
linuxaio_poll (EV_P_ ev_tstamp timeout) |
|||
{ |
|||
int submitted; |
|||
|
|||
/* first phase: submit new iocbs */ |
|||
|
|||
/* io_submit might return less than the requested number of iocbs */ |
|||
/* this is, afaics, only because of errors, but we go by the book and use a loop, */ |
|||
/* which allows us to pinpoint the errornous iocb */ |
|||
for (submitted = 0; submitted < linuxaio_submitcnt; ) |
|||
{ |
|||
int res = ev_io_submit (linuxaio_ctx, linuxaio_submitcnt - submitted, linuxaio_submits + submitted); |
|||
|
|||
if (res < 0) |
|||
if (errno == EAGAIN) |
|||
{ |
|||
/* This happens when the ring buffer is full, at least. I assume this means |
|||
* that the event was queued synchronously during io_submit, and thus |
|||
* the buffer overflowd. |
|||
* In this case, we just try next loop iteration. |
|||
*/ |
|||
memcpy (linuxaio_submits, linuxaio_submits + submitted, (linuxaio_submitcnt - submitted) * sizeof (*linuxaio_submits)); |
|||
linuxaio_submitcnt -= submitted; |
|||
timeout = 0; |
|||
break; |
|||
} |
|||
else |
|||
/* TODO: we get EAGAIN when the ring buffer is full for some reason */ |
|||
/* TODO: should we always just try next time? */ |
|||
ev_syserr ("(libev) io_submit"); |
|||
|
|||
submitted += res; |
|||
} |
|||
|
|||
linuxaio_submitcnt = 0; |
|||
|
|||
/* second phase: fetch and parse events */ |
|||
|
|||
linuxaio_get_events (EV_A_ timeout); |
|||
} |
|||
|
|||
inline_size |
|||
int |
|||
linuxaio_init (EV_P_ int flags) |
|||
{ |
|||
/* would be great to have a nice test for IOCB_CMD_POLL instead */ |
|||
if (ev_linux_version () < 0x041200) /* 4.18 introduced IOCB_CMD_POLL */ |
|||
return 0; |
|||
|
|||
if (ev_io_setup (EV_LINUXAIO_DEPTH, &linuxaio_ctx) < 0) |
|||
return 0; |
|||
|
|||
backend_modify = linuxaio_modify; |
|||
backend_poll = linuxaio_poll; |
|||
|
|||
linuxaio_iocbpmax = 0; |
|||
linuxaio_iocbps = 0; |
|||
|
|||
linuxaio_submits = 0; |
|||
linuxaio_submitmax = 0; |
|||
linuxaio_submitcnt = 0; |
|||
|
|||
return EVBACKEND_LINUXAIO; |
|||
} |
|||
|
|||
inline_size |
|||
void |
|||
linuxaio_destroy (EV_P) |
|||
{ |
|||
linuxaio_free_iocbp (EV_A); |
|||
ev_io_destroy (linuxaio_ctx); |
|||
} |
|||
|
|||
inline_size |
|||
void |
|||
linuxaio_fork (EV_P) |
|||
{ |
|||
abort ();//D |
|||
} |
|||
|
|||
Write
Preview
Loading…
Cancel
Save
Reference in new issue