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/* |
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* libev linux aio fd activity backend |
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* |
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* Copyright (c) 2019 Marc Alexander Lehmann |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without modifica- |
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* tion, are permitted provided that the following conditions are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright notice, |
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* this list of conditions and the following disclaimer. |
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* |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- |
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* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- |
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* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- |
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* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
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* OF THE POSSIBILITY OF SUCH DAMAGE. |
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* |
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* Alternatively, the contents of this file may be used under the terms of |
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* the GNU General Public License ("GPL") version 2 or any later version, |
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* in which case the provisions of the GPL are applicable instead of |
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* the above. If you wish to allow the use of your version of this file |
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* only under the terms of the GPL and not to allow others to use your |
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* version of this file under the BSD license, indicate your decision |
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* by deleting the provisions above and replace them with the notice |
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* and other provisions required by the GPL. If you do not delete the |
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* provisions above, a recipient may use your version of this file under |
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* either the BSD or the GPL. |
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*/ |
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/* |
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* general notes about linux aio: |
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* |
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* a) at first, the linux aio IOCB_CMD_POLL functionality introduced in |
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* 4.18 looks too good to be true: both watchers and events can be |
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* batched, and events can even be handled in userspace using |
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* a ring buffer shared with the kernel. watchers can be canceled |
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* regardless of whether the fd has been closed. no problems with fork. |
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* ok, the ring buffer is 200% undocumented (there isn't even a |
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* header file), but otherwise, it's pure bliss! |
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* b) ok, watchers are one-shot, so you have to re-arm active ones |
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* on every iteration. so much for syscall-less event handling, |
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* but at least these re-arms can be batched, no big deal, right? |
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* c) well, linux as usual: the documentation lies to you: io_submit |
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* sometimes returns EINVAL because the kernel doesn't feel like |
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* handling your poll mask - ttys can be polled for POLLOUT, |
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* POLLOUT|POLLIN, but polling for POLLIN fails. just great, |
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* so we have to fall back to something else (hello, epoll), |
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* but at least the fallback can be slow, because these are |
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* exceptional cases, right? |
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* d) hmm, you have to tell the kernel the maximum number of watchers |
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* you want to queue when initialising the aio context. but of |
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* course the real limit is magically calculated in the kernel, and |
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* is often higher then we asked for. so we just have to destroy |
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* the aio context and re-create it a bit larger if we hit the limit. |
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* (starts to remind you of epoll? well, it's a bit more deterministic |
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* and less gambling, but still ugly as hell). |
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* e) that's when you find out you can also hit an arbitrary system-wide |
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* limit. or the kernel simply doesn't want to handle your watchers. |
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* what the fuck do we do then? you guessed it, in the middle |
70
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* of event handling we have to switch to 100% epoll polling. and |
71
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* that better is as fast as normal epoll polling, so you practically |
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* have to use the normal epoll backend with all its quirks. |
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* f) end result of this train wreck: it inherits all the disadvantages |
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* from epoll, while adding a number on its own. why even bother to use |
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* it? because if conditions are right and your fds are supported and you |
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* don't hit a limit, this backend is actually faster, doesn't gamble with |
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* your fds, batches watchers and events and doesn't require costly state |
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* recreates. well, until it does. |
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* g) all of this makes this backend use almost twice as much code as epoll. |
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* which in turn uses twice as much code as poll. and that#s not counting |
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* the fact that this backend also depends on the epoll backend, making |
82
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* it three times as much code as poll, or kqueue. |
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* h) bleah. why can't linux just do kqueue. sure kqueue is ugly, but by now |
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* it's clear that whatever linux comes up with is far, far, far worse. |
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*/ |
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87
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#include /* actually linux/time.h, but we must assume they are compatible */ |
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#include |
89
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#include |
90
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91
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/*****************************************************************************/ |
92
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/* syscall wrapdadoop - this section has the raw api/abi definitions */ |
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94
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#include /* no glibc wrappers */ |
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96
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/* aio_abi.h is not versioned in any way, so we cannot test for its existance */ |
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#define IOCB_CMD_POLL 5 |
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99
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/* taken from linux/fs/aio.c. yup, that's a .c file. |
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* not only is this totally undocumented, not even the source code |
101
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* can tell you what the future semantics of compat_features and |
102
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* incompat_features are, or what header_length actually is for. |
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*/ |
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#define AIO_RING_MAGIC 0xa10a10a1 |
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#define EV_AIO_RING_INCOMPAT_FEATURES 0 |
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struct aio_ring |
107
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{ |
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unsigned id; /* kernel internal index number */ |
109
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unsigned nr; /* number of io_events */ |
110
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unsigned head; /* Written to by userland or by kernel. */ |
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unsigned tail; |
112
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113
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unsigned magic; |
114
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unsigned compat_features; |
115
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unsigned incompat_features; |
116
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unsigned header_length; /* size of aio_ring */ |
117
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118
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struct io_event io_events[0]; |
119
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}; |
120
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121
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inline_size |
122
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int |
123
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0
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evsys_io_setup (unsigned nr_events, aio_context_t *ctx_idp) |
124
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{ |
125
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0
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return ev_syscall2 (SYS_io_setup, nr_events, ctx_idp); |
126
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} |
127
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128
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inline_size |
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int |
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0
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evsys_io_destroy (aio_context_t ctx_id) |
131
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{ |
132
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0
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return ev_syscall1 (SYS_io_destroy, ctx_id); |
133
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} |
134
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135
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inline_size |
136
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int |
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0
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evsys_io_submit (aio_context_t ctx_id, long nr, struct iocb *cbp[]) |
138
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{ |
139
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0
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return ev_syscall3 (SYS_io_submit, ctx_id, nr, cbp); |
140
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} |
141
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142
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inline_size |
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int |
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0
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evsys_io_cancel (aio_context_t ctx_id, struct iocb *cbp, struct io_event *result) |
145
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{ |
146
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0
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return ev_syscall3 (SYS_io_cancel, ctx_id, cbp, result); |
147
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} |
148
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149
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inline_size |
150
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int |
151
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0
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evsys_io_getevents (aio_context_t ctx_id, long min_nr, long nr, struct io_event *events, struct timespec *timeout) |
152
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{ |
153
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0
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return ev_syscall5 (SYS_io_getevents, ctx_id, min_nr, nr, events, timeout); |
154
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} |
155
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156
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/*****************************************************************************/ |
157
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/* actual backed implementation */ |
158
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159
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ecb_cold |
160
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static int |
161
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0
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linuxaio_nr_events (EV_P) |
162
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{ |
163
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/* we start with 16 iocbs and incraese from there |
164
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* that's tiny, but the kernel has a rather low system-wide |
165
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* limit that can be reached quickly, so let's be parsimonious |
166
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* with this resource. |
167
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* Rest assured, the kernel generously rounds up small and big numbers |
168
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* in different ways (but doesn't seem to charge you for it). |
169
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* The 15 here is because the kernel usually has a power of two as aio-max-nr, |
170
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* and this helps to take advantage of that limit. |
171
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*/ |
172
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173
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/* we try to fill 4kB pages exactly. |
174
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* the ring buffer header is 32 bytes, every io event is 32 bytes. |
175
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* the kernel takes the io requests number, doubles it, adds 2 |
176
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* and adds the ring buffer. |
177
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* the way we use this is by starting low, and then roughly doubling the |
178
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* size each time we hit a limit. |
179
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*/ |
180
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181
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0
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int requests = 15 << linuxaio_iteration; |
182
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0
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int one_page = (4096 |
183
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/ sizeof (struct io_event) ) / 2; /* how many fit into one page */ |
184
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0
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int first_page = ((4096 - sizeof (struct aio_ring)) |
185
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/ sizeof (struct io_event) - 2) / 2; /* how many fit into the first page */ |
186
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187
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/* if everything fits into one page, use count exactly */ |
188
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0
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0
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if (requests > first_page) |
189
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/* otherwise, round down to full pages and add the first page */ |
190
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0
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requests = requests / one_page * one_page + first_page; |
191
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192
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0
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return requests; |
193
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} |
194
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195
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/* we use out own wrapper structure in case we ever want to do something "clever" */ |
196
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typedef struct aniocb |
197
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{ |
198
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struct iocb io; |
199
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/*int inuse;*/ |
200
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} *ANIOCBP; |
201
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202
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inline_size |
203
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void |
204
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0
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linuxaio_array_needsize_iocbp (ANIOCBP *base, int offset, int count) |
205
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{ |
206
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0
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0
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while (count--) |
207
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{ |
208
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/* TODO: quite the overhead to allocate every iocb separately, maybe use our own allocator? */ |
209
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0
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ANIOCBP iocb = (ANIOCBP)ev_malloc (sizeof (*iocb)); |
210
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211
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/* full zero initialise is probably not required at the moment, but |
212
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* this is not well documented, so we better do it. |
213
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*/ |
214
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0
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memset (iocb, 0, sizeof (*iocb)); |
215
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216
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0
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iocb->io.aio_lio_opcode = IOCB_CMD_POLL; |
217
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0
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iocb->io.aio_fildes = offset; |
218
|
|
|
|
|
|
|
|
219
|
0
|
|
|
|
|
|
base [offset++] = iocb; |
220
|
|
|
|
|
|
|
} |
221
|
0
|
|
|
|
|
|
} |
222
|
|
|
|
|
|
|
|
223
|
|
|
|
|
|
|
ecb_cold |
224
|
|
|
|
|
|
|
static void |
225
|
0
|
|
|
|
|
|
linuxaio_free_iocbp (EV_P) |
226
|
|
|
|
|
|
|
{ |
227
|
0
|
0
|
|
|
|
|
while (linuxaio_iocbpmax--) |
228
|
0
|
|
|
|
|
|
ev_free (linuxaio_iocbps [linuxaio_iocbpmax]); |
229
|
|
|
|
|
|
|
|
230
|
0
|
|
|
|
|
|
linuxaio_iocbpmax = 0; /* next resize will completely reallocate the array, at some overhead */ |
231
|
0
|
|
|
|
|
|
} |
232
|
|
|
|
|
|
|
|
233
|
|
|
|
|
|
|
static void |
234
|
0
|
|
|
|
|
|
linuxaio_modify (EV_P_ int fd, int oev, int nev) |
235
|
|
|
|
|
|
|
{ |
236
|
0
|
0
|
|
|
|
|
array_needsize (ANIOCBP, linuxaio_iocbps, linuxaio_iocbpmax, fd + 1, linuxaio_array_needsize_iocbp); |
237
|
0
|
|
|
|
|
|
ANIOCBP iocb = linuxaio_iocbps [fd]; |
238
|
0
|
|
|
|
|
|
ANFD *anfd = &anfds [fd]; |
239
|
|
|
|
|
|
|
|
240
|
0
|
0
|
|
|
|
|
if (ecb_expect_false (iocb->io.aio_reqprio < 0)) |
241
|
|
|
|
|
|
|
{ |
242
|
|
|
|
|
|
|
/* we handed this fd over to epoll, so undo this first */ |
243
|
|
|
|
|
|
|
/* we do it manually because the optimisations on epoll_modify won't do us any good */ |
244
|
0
|
|
|
|
|
|
epoll_ctl (backend_fd, EPOLL_CTL_DEL, fd, 0); |
245
|
0
|
|
|
|
|
|
anfd->emask = 0; |
246
|
0
|
|
|
|
|
|
iocb->io.aio_reqprio = 0; |
247
|
|
|
|
|
|
|
} |
248
|
0
|
0
|
|
|
|
|
else if (ecb_expect_false (iocb->io.aio_buf)) |
249
|
|
|
|
|
|
|
{ |
250
|
|
|
|
|
|
|
/* iocb active, so cancel it first before resubmit */ |
251
|
|
|
|
|
|
|
/* this assumes we only ever get one call per fd per loop iteration */ |
252
|
|
|
|
|
|
|
for (;;) |
253
|
|
|
|
|
|
|
{ |
254
|
|
|
|
|
|
|
/* on all relevant kernels, io_cancel fails with EINPROGRESS on "success" */ |
255
|
0
|
0
|
|
|
|
|
if (ecb_expect_false (evsys_io_cancel (linuxaio_ctx, &iocb->io, (struct io_event *)0) == 0)) |
256
|
0
|
|
|
|
|
|
break; |
257
|
|
|
|
|
|
|
|
258
|
0
|
0
|
|
|
|
|
if (ecb_expect_true (errno == EINPROGRESS)) |
259
|
0
|
|
|
|
|
|
break; |
260
|
|
|
|
|
|
|
|
261
|
|
|
|
|
|
|
/* the EINPROGRESS test is for nicer error message. clumsy. */ |
262
|
0
|
0
|
|
|
|
|
if (errno != EINTR) |
263
|
|
|
|
|
|
|
{ |
264
|
|
|
|
|
|
|
assert (("libev: linuxaio unexpected io_cancel failed", errno != EINTR && errno != EINPROGRESS)); |
265
|
0
|
|
|
|
|
|
break; |
266
|
|
|
|
|
|
|
} |
267
|
0
|
|
|
|
|
|
} |
268
|
|
|
|
|
|
|
|
269
|
|
|
|
|
|
|
/* increment generation counter to avoid handling old events */ |
270
|
0
|
|
|
|
|
|
++anfd->egen; |
271
|
|
|
|
|
|
|
} |
272
|
|
|
|
|
|
|
|
273
|
0
|
|
|
|
|
|
iocb->io.aio_buf = (nev & EV_READ ? POLLIN : 0) |
274
|
0
|
0
|
|
|
|
|
| (nev & EV_WRITE ? POLLOUT : 0); |
275
|
|
|
|
|
|
|
|
276
|
0
|
0
|
|
|
|
|
if (nev) |
277
|
|
|
|
|
|
|
{ |
278
|
0
|
|
|
|
|
|
iocb->io.aio_data = (uint32_t)fd | ((__u64)(uint32_t)anfd->egen << 32); |
279
|
|
|
|
|
|
|
|
280
|
|
|
|
|
|
|
/* queue iocb up for io_submit */ |
281
|
|
|
|
|
|
|
/* this assumes we only ever get one call per fd per loop iteration */ |
282
|
0
|
|
|
|
|
|
++linuxaio_submitcnt; |
283
|
0
|
0
|
|
|
|
|
array_needsize (struct iocb *, linuxaio_submits, linuxaio_submitmax, linuxaio_submitcnt, array_needsize_noinit); |
284
|
0
|
|
|
|
|
|
linuxaio_submits [linuxaio_submitcnt - 1] = &iocb->io; |
285
|
|
|
|
|
|
|
} |
286
|
0
|
|
|
|
|
|
} |
287
|
|
|
|
|
|
|
|
288
|
|
|
|
|
|
|
static void |
289
|
0
|
|
|
|
|
|
linuxaio_epoll_cb (EV_P_ struct ev_io *w, int revents) |
290
|
|
|
|
|
|
|
{ |
291
|
0
|
|
|
|
|
|
epoll_poll (EV_A_ 0); |
292
|
0
|
|
|
|
|
|
} |
293
|
|
|
|
|
|
|
|
294
|
|
|
|
|
|
|
inline_speed |
295
|
|
|
|
|
|
|
void |
296
|
0
|
|
|
|
|
|
linuxaio_fd_rearm (EV_P_ int fd) |
297
|
|
|
|
|
|
|
{ |
298
|
0
|
|
|
|
|
|
anfds [fd].events = 0; |
299
|
0
|
|
|
|
|
|
linuxaio_iocbps [fd]->io.aio_buf = 0; |
300
|
0
|
|
|
|
|
|
fd_change (EV_A_ fd, EV_ANFD_REIFY); |
301
|
0
|
|
|
|
|
|
} |
302
|
|
|
|
|
|
|
|
303
|
|
|
|
|
|
|
static void |
304
|
0
|
|
|
|
|
|
linuxaio_parse_events (EV_P_ struct io_event *ev, int nr) |
305
|
|
|
|
|
|
|
{ |
306
|
0
|
0
|
|
|
|
|
while (nr) |
307
|
|
|
|
|
|
|
{ |
308
|
0
|
|
|
|
|
|
int fd = ev->data & 0xffffffff; |
309
|
0
|
|
|
|
|
|
uint32_t gen = ev->data >> 32; |
310
|
0
|
|
|
|
|
|
int res = ev->res; |
311
|
|
|
|
|
|
|
|
312
|
|
|
|
|
|
|
assert (("libev: iocb fd must be in-bounds", fd >= 0 && fd < anfdmax)); |
313
|
|
|
|
|
|
|
|
314
|
|
|
|
|
|
|
/* only accept events if generation counter matches */ |
315
|
0
|
0
|
|
|
|
|
if (ecb_expect_true (gen == (uint32_t)anfds [fd].egen)) |
316
|
|
|
|
|
|
|
{ |
317
|
|
|
|
|
|
|
/* feed events, we do not expect or handle POLLNVAL */ |
318
|
0
|
|
|
|
|
|
fd_event ( |
319
|
|
|
|
|
|
|
EV_A_ |
320
|
|
|
|
|
|
|
fd, |
321
|
0
|
0
|
|
|
|
|
(res & (POLLOUT | POLLERR | POLLHUP) ? EV_WRITE : 0) |
322
|
0
|
|
|
|
|
|
| (res & (POLLIN | POLLERR | POLLHUP) ? EV_READ : 0) |
323
|
|
|
|
|
|
|
); |
324
|
|
|
|
|
|
|
|
325
|
|
|
|
|
|
|
/* linux aio is oneshot: rearm fd. TODO: this does more work than strictly needed */ |
326
|
0
|
|
|
|
|
|
linuxaio_fd_rearm (EV_A_ fd); |
327
|
|
|
|
|
|
|
} |
328
|
|
|
|
|
|
|
|
329
|
0
|
|
|
|
|
|
--nr; |
330
|
0
|
|
|
|
|
|
++ev; |
331
|
|
|
|
|
|
|
} |
332
|
0
|
|
|
|
|
|
} |
333
|
|
|
|
|
|
|
|
334
|
|
|
|
|
|
|
/* get any events from ring buffer, return true if any were handled */ |
335
|
|
|
|
|
|
|
static int |
336
|
0
|
|
|
|
|
|
linuxaio_get_events_from_ring (EV_P) |
337
|
|
|
|
|
|
|
{ |
338
|
0
|
|
|
|
|
|
struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx; |
339
|
|
|
|
|
|
|
unsigned head, tail; |
340
|
|
|
|
|
|
|
|
341
|
|
|
|
|
|
|
/* the kernel reads and writes both of these variables, */ |
342
|
|
|
|
|
|
|
/* as a C extension, we assume that volatile use here */ |
343
|
|
|
|
|
|
|
/* both makes reads atomic and once-only */ |
344
|
0
|
|
|
|
|
|
head = *(volatile unsigned *)&ring->head; |
345
|
0
|
|
|
|
|
|
ECB_MEMORY_FENCE_ACQUIRE; |
346
|
0
|
|
|
|
|
|
tail = *(volatile unsigned *)&ring->tail; |
347
|
|
|
|
|
|
|
|
348
|
0
|
0
|
|
|
|
|
if (head == tail) |
349
|
0
|
|
|
|
|
|
return 0; |
350
|
|
|
|
|
|
|
|
351
|
|
|
|
|
|
|
/* parse all available events, but only once, to avoid starvation */ |
352
|
0
|
0
|
|
|
|
|
if (ecb_expect_true (tail > head)) /* normal case around */ |
353
|
0
|
|
|
|
|
|
linuxaio_parse_events (EV_A_ ring->io_events + head, tail - head); |
354
|
|
|
|
|
|
|
else /* wrapped around */ |
355
|
|
|
|
|
|
|
{ |
356
|
0
|
|
|
|
|
|
linuxaio_parse_events (EV_A_ ring->io_events + head, ring->nr - head); |
357
|
0
|
|
|
|
|
|
linuxaio_parse_events (EV_A_ ring->io_events, tail); |
358
|
|
|
|
|
|
|
} |
359
|
|
|
|
|
|
|
|
360
|
0
|
|
|
|
|
|
ECB_MEMORY_FENCE_RELEASE; |
361
|
|
|
|
|
|
|
/* as an extension to C, we hope that the volatile will make this atomic and once-only */ |
362
|
0
|
|
|
|
|
|
*(volatile unsigned *)&ring->head = tail; |
363
|
|
|
|
|
|
|
|
364
|
0
|
|
|
|
|
|
return 1; |
365
|
|
|
|
|
|
|
} |
366
|
|
|
|
|
|
|
|
367
|
|
|
|
|
|
|
inline_size |
368
|
|
|
|
|
|
|
int |
369
|
0
|
|
|
|
|
|
linuxaio_ringbuf_valid (EV_P) |
370
|
|
|
|
|
|
|
{ |
371
|
0
|
|
|
|
|
|
struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx; |
372
|
|
|
|
|
|
|
|
373
|
0
|
|
|
|
|
|
return ecb_expect_true (ring->magic == AIO_RING_MAGIC) |
374
|
0
|
0
|
|
|
|
|
&& ring->incompat_features == EV_AIO_RING_INCOMPAT_FEATURES |
375
|
0
|
0
|
|
|
|
|
&& ring->header_length == sizeof (struct aio_ring); /* TODO: or use it to find io_event[0]? */ |
|
|
0
|
|
|
|
|
|
376
|
|
|
|
|
|
|
} |
377
|
|
|
|
|
|
|
|
378
|
|
|
|
|
|
|
/* read at least one event from kernel, or timeout */ |
379
|
|
|
|
|
|
|
inline_size |
380
|
|
|
|
|
|
|
void |
381
|
0
|
|
|
|
|
|
linuxaio_get_events (EV_P_ ev_tstamp timeout) |
382
|
|
|
|
|
|
|
{ |
383
|
|
|
|
|
|
|
struct timespec ts; |
384
|
|
|
|
|
|
|
struct io_event ioev[8]; /* 256 octet stack space */ |
385
|
0
|
|
|
|
|
|
int want = 1; /* how many events to request */ |
386
|
0
|
|
|
|
|
|
int ringbuf_valid = linuxaio_ringbuf_valid (EV_A); |
387
|
|
|
|
|
|
|
|
388
|
0
|
0
|
|
|
|
|
if (ecb_expect_true (ringbuf_valid)) |
389
|
|
|
|
|
|
|
{ |
390
|
|
|
|
|
|
|
/* if the ring buffer has any events, we don't wait or call the kernel at all */ |
391
|
0
|
0
|
|
|
|
|
if (linuxaio_get_events_from_ring (EV_A)) |
392
|
0
|
|
|
|
|
|
return; |
393
|
|
|
|
|
|
|
|
394
|
|
|
|
|
|
|
/* if the ring buffer is empty, and we don't have a timeout, then don't call the kernel */ |
395
|
0
|
0
|
|
|
|
|
if (!timeout) |
396
|
0
|
|
|
|
|
|
return; |
397
|
|
|
|
|
|
|
} |
398
|
|
|
|
|
|
|
else |
399
|
|
|
|
|
|
|
/* no ringbuffer, request slightly larger batch */ |
400
|
0
|
|
|
|
|
|
want = sizeof (ioev) / sizeof (ioev [0]); |
401
|
|
|
|
|
|
|
|
402
|
|
|
|
|
|
|
/* no events, so wait for some |
403
|
|
|
|
|
|
|
* for fairness reasons, we do this in a loop, to fetch all events |
404
|
|
|
|
|
|
|
*/ |
405
|
|
|
|
|
|
|
for (;;) |
406
|
|
|
|
|
|
|
{ |
407
|
|
|
|
|
|
|
int res; |
408
|
|
|
|
|
|
|
|
409
|
0
|
0
|
|
|
|
|
EV_RELEASE_CB; |
410
|
|
|
|
|
|
|
|
411
|
0
|
|
|
|
|
|
EV_TS_SET (ts, timeout); |
412
|
0
|
|
|
|
|
|
res = evsys_io_getevents (linuxaio_ctx, 1, want, ioev, &ts); |
413
|
|
|
|
|
|
|
|
414
|
0
|
0
|
|
|
|
|
EV_ACQUIRE_CB; |
415
|
|
|
|
|
|
|
|
416
|
0
|
0
|
|
|
|
|
if (res < 0) |
417
|
0
|
0
|
|
|
|
|
if (errno == EINTR) |
418
|
|
|
|
|
|
|
/* ignored, retry */; |
419
|
|
|
|
|
|
|
else |
420
|
0
|
|
|
|
|
|
ev_syserr ("(libev) linuxaio io_getevents"); |
421
|
0
|
0
|
|
|
|
|
else if (res) |
422
|
|
|
|
|
|
|
{ |
423
|
|
|
|
|
|
|
/* at least one event available, handle them */ |
424
|
0
|
|
|
|
|
|
linuxaio_parse_events (EV_A_ ioev, res); |
425
|
|
|
|
|
|
|
|
426
|
0
|
0
|
|
|
|
|
if (ecb_expect_true (ringbuf_valid)) |
427
|
|
|
|
|
|
|
{ |
428
|
|
|
|
|
|
|
/* if we have a ring buffer, handle any remaining events in it */ |
429
|
0
|
|
|
|
|
|
linuxaio_get_events_from_ring (EV_A); |
430
|
|
|
|
|
|
|
|
431
|
|
|
|
|
|
|
/* at this point, we should have handled all outstanding events */ |
432
|
0
|
|
|
|
|
|
break; |
433
|
|
|
|
|
|
|
} |
434
|
0
|
0
|
|
|
|
|
else if (res < want) |
435
|
|
|
|
|
|
|
/* otherwise, if there were fewere events than we wanted, we assume there are no more */ |
436
|
0
|
|
|
|
|
|
break; |
437
|
|
|
|
|
|
|
} |
438
|
|
|
|
|
|
|
else |
439
|
0
|
|
|
|
|
|
break; /* no events from the kernel, we are done */ |
440
|
|
|
|
|
|
|
|
441
|
0
|
|
|
|
|
|
timeout = EV_TS_CONST (0.); /* only wait in the first iteration */ |
442
|
0
|
|
|
|
|
|
} |
443
|
|
|
|
|
|
|
} |
444
|
|
|
|
|
|
|
|
445
|
|
|
|
|
|
|
inline_size |
446
|
|
|
|
|
|
|
int |
447
|
0
|
|
|
|
|
|
linuxaio_io_setup (EV_P) |
448
|
|
|
|
|
|
|
{ |
449
|
0
|
|
|
|
|
|
linuxaio_ctx = 0; |
450
|
0
|
|
|
|
|
|
return evsys_io_setup (linuxaio_nr_events (EV_A), &linuxaio_ctx); |
451
|
|
|
|
|
|
|
} |
452
|
|
|
|
|
|
|
|
453
|
|
|
|
|
|
|
static void |
454
|
0
|
|
|
|
|
|
linuxaio_poll (EV_P_ ev_tstamp timeout) |
455
|
|
|
|
|
|
|
{ |
456
|
|
|
|
|
|
|
int submitted; |
457
|
|
|
|
|
|
|
|
458
|
|
|
|
|
|
|
/* first phase: submit new iocbs */ |
459
|
|
|
|
|
|
|
|
460
|
|
|
|
|
|
|
/* io_submit might return less than the requested number of iocbs */ |
461
|
|
|
|
|
|
|
/* this is, afaics, only because of errors, but we go by the book and use a loop, */ |
462
|
|
|
|
|
|
|
/* which allows us to pinpoint the erroneous iocb */ |
463
|
0
|
0
|
|
|
|
|
for (submitted = 0; submitted < linuxaio_submitcnt; ) |
464
|
|
|
|
|
|
|
{ |
465
|
0
|
|
|
|
|
|
int res = evsys_io_submit (linuxaio_ctx, linuxaio_submitcnt - submitted, linuxaio_submits + submitted); |
466
|
|
|
|
|
|
|
|
467
|
0
|
0
|
|
|
|
|
if (ecb_expect_false (res < 0)) |
468
|
0
|
0
|
|
|
|
|
if (errno == EINVAL) |
469
|
|
|
|
|
|
|
{ |
470
|
|
|
|
|
|
|
/* This happens for unsupported fds, officially, but in my testing, |
471
|
|
|
|
|
|
|
* also randomly happens for supported fds. We fall back to good old |
472
|
|
|
|
|
|
|
* poll() here, under the assumption that this is a very rare case. |
473
|
|
|
|
|
|
|
* See https://lore.kernel.org/patchwork/patch/1047453/ to see |
474
|
|
|
|
|
|
|
* discussion about such a case (ttys) where polling for POLLIN |
475
|
|
|
|
|
|
|
* fails but POLLIN|POLLOUT works. |
476
|
|
|
|
|
|
|
*/ |
477
|
0
|
|
|
|
|
|
struct iocb *iocb = linuxaio_submits [submitted]; |
478
|
0
|
|
|
|
|
|
epoll_modify (EV_A_ iocb->aio_fildes, 0, anfds [iocb->aio_fildes].events); |
479
|
0
|
|
|
|
|
|
iocb->aio_reqprio = -1; /* mark iocb as epoll */ |
480
|
|
|
|
|
|
|
|
481
|
0
|
|
|
|
|
|
res = 1; /* skip this iocb - another iocb, another chance */ |
482
|
|
|
|
|
|
|
} |
483
|
0
|
0
|
|
|
|
|
else if (errno == EAGAIN) |
484
|
|
|
|
|
|
|
{ |
485
|
|
|
|
|
|
|
/* This happens when the ring buffer is full, or some other shit we |
486
|
|
|
|
|
|
|
* don't know and isn't documented. Most likely because we have too |
487
|
|
|
|
|
|
|
* many requests and linux aio can't be assed to handle them. |
488
|
|
|
|
|
|
|
* In this case, we try to allocate a larger ring buffer, freeing |
489
|
|
|
|
|
|
|
* ours first. This might fail, in which case we have to fall back to 100% |
490
|
|
|
|
|
|
|
* epoll. |
491
|
|
|
|
|
|
|
* God, how I hate linux not getting its act together. Ever. |
492
|
|
|
|
|
|
|
*/ |
493
|
0
|
|
|
|
|
|
evsys_io_destroy (linuxaio_ctx); |
494
|
0
|
|
|
|
|
|
linuxaio_submitcnt = 0; |
495
|
|
|
|
|
|
|
|
496
|
|
|
|
|
|
|
/* rearm all fds with active iocbs */ |
497
|
|
|
|
|
|
|
{ |
498
|
|
|
|
|
|
|
int fd; |
499
|
0
|
0
|
|
|
|
|
for (fd = 0; fd < linuxaio_iocbpmax; ++fd) |
500
|
0
|
0
|
|
|
|
|
if (linuxaio_iocbps [fd]->io.aio_buf) |
501
|
0
|
|
|
|
|
|
linuxaio_fd_rearm (EV_A_ fd); |
502
|
|
|
|
|
|
|
} |
503
|
|
|
|
|
|
|
|
504
|
0
|
|
|
|
|
|
++linuxaio_iteration; |
505
|
0
|
0
|
|
|
|
|
if (linuxaio_io_setup (EV_A) < 0) |
506
|
|
|
|
|
|
|
{ |
507
|
|
|
|
|
|
|
/* TODO: rearm all and recreate epoll backend from scratch */ |
508
|
|
|
|
|
|
|
/* TODO: might be more prudent? */ |
509
|
|
|
|
|
|
|
|
510
|
|
|
|
|
|
|
/* to bad, we can't get a new aio context, go 100% epoll */ |
511
|
0
|
|
|
|
|
|
linuxaio_free_iocbp (EV_A); |
512
|
0
|
|
|
|
|
|
ev_io_stop (EV_A_ &linuxaio_epoll_w); |
513
|
0
|
|
|
|
|
|
ev_ref (EV_A); |
514
|
0
|
|
|
|
|
|
linuxaio_ctx = 0; |
515
|
|
|
|
|
|
|
|
516
|
0
|
|
|
|
|
|
backend = EVBACKEND_EPOLL; |
517
|
0
|
|
|
|
|
|
backend_modify = epoll_modify; |
518
|
0
|
|
|
|
|
|
backend_poll = epoll_poll; |
519
|
|
|
|
|
|
|
} |
520
|
|
|
|
|
|
|
|
521
|
0
|
|
|
|
|
|
timeout = EV_TS_CONST (0.); |
522
|
|
|
|
|
|
|
/* it's easiest to handle this mess in another iteration */ |
523
|
0
|
|
|
|
|
|
return; |
524
|
|
|
|
|
|
|
} |
525
|
0
|
0
|
|
|
|
|
else if (errno == EBADF) |
526
|
|
|
|
|
|
|
{ |
527
|
|
|
|
|
|
|
assert (("libev: event loop rejected bad fd", errno != EBADF)); |
528
|
0
|
|
|
|
|
|
fd_kill (EV_A_ linuxaio_submits [submitted]->aio_fildes); |
529
|
|
|
|
|
|
|
|
530
|
0
|
|
|
|
|
|
res = 1; /* skip this iocb */ |
531
|
|
|
|
|
|
|
} |
532
|
0
|
0
|
|
|
|
|
else if (errno == EINTR) /* not seen in reality, not documented */ |
533
|
0
|
|
|
|
|
|
res = 0; /* silently ignore and retry */ |
534
|
|
|
|
|
|
|
else |
535
|
|
|
|
|
|
|
{ |
536
|
0
|
|
|
|
|
|
ev_syserr ("(libev) linuxaio io_submit"); |
537
|
0
|
|
|
|
|
|
res = 0; |
538
|
|
|
|
|
|
|
} |
539
|
|
|
|
|
|
|
|
540
|
0
|
|
|
|
|
|
submitted += res; |
541
|
|
|
|
|
|
|
} |
542
|
|
|
|
|
|
|
|
543
|
0
|
|
|
|
|
|
linuxaio_submitcnt = 0; |
544
|
|
|
|
|
|
|
|
545
|
|
|
|
|
|
|
/* second phase: fetch and parse events */ |
546
|
|
|
|
|
|
|
|
547
|
0
|
|
|
|
|
|
linuxaio_get_events (EV_A_ timeout); |
548
|
|
|
|
|
|
|
} |
549
|
|
|
|
|
|
|
|
550
|
|
|
|
|
|
|
inline_size |
551
|
|
|
|
|
|
|
int |
552
|
0
|
|
|
|
|
|
linuxaio_init (EV_P_ int flags) |
553
|
|
|
|
|
|
|
{ |
554
|
|
|
|
|
|
|
/* would be great to have a nice test for IOCB_CMD_POLL instead */ |
555
|
|
|
|
|
|
|
/* also: test some semi-common fd types, such as files and ttys in recommended_backends */ |
556
|
|
|
|
|
|
|
/* 4.18 introduced IOCB_CMD_POLL, 4.19 made epoll work, and we need that */ |
557
|
0
|
0
|
|
|
|
|
if (ev_linux_version () < 0x041300) |
558
|
0
|
|
|
|
|
|
return 0; |
559
|
|
|
|
|
|
|
|
560
|
0
|
0
|
|
|
|
|
if (!epoll_init (EV_A_ 0)) |
561
|
0
|
|
|
|
|
|
return 0; |
562
|
|
|
|
|
|
|
|
563
|
0
|
|
|
|
|
|
linuxaio_iteration = 0; |
564
|
|
|
|
|
|
|
|
565
|
0
|
0
|
|
|
|
|
if (linuxaio_io_setup (EV_A) < 0) |
566
|
|
|
|
|
|
|
{ |
567
|
0
|
|
|
|
|
|
epoll_destroy (EV_A); |
568
|
0
|
|
|
|
|
|
return 0; |
569
|
|
|
|
|
|
|
} |
570
|
|
|
|
|
|
|
|
571
|
0
|
|
|
|
|
|
ev_io_init (&linuxaio_epoll_w, linuxaio_epoll_cb, backend_fd, EV_READ); |
572
|
0
|
|
|
|
|
|
ev_set_priority (&linuxaio_epoll_w, EV_MAXPRI); |
573
|
0
|
|
|
|
|
|
ev_io_start (EV_A_ &linuxaio_epoll_w); |
574
|
0
|
|
|
|
|
|
ev_unref (EV_A); /* watcher should not keep loop alive */ |
575
|
|
|
|
|
|
|
|
576
|
0
|
|
|
|
|
|
backend_modify = linuxaio_modify; |
577
|
0
|
|
|
|
|
|
backend_poll = linuxaio_poll; |
578
|
|
|
|
|
|
|
|
579
|
0
|
|
|
|
|
|
linuxaio_iocbpmax = 0; |
580
|
0
|
|
|
|
|
|
linuxaio_iocbps = 0; |
581
|
|
|
|
|
|
|
|
582
|
0
|
|
|
|
|
|
linuxaio_submits = 0; |
583
|
0
|
|
|
|
|
|
linuxaio_submitmax = 0; |
584
|
0
|
|
|
|
|
|
linuxaio_submitcnt = 0; |
585
|
|
|
|
|
|
|
|
586
|
0
|
|
|
|
|
|
return EVBACKEND_LINUXAIO; |
587
|
|
|
|
|
|
|
} |
588
|
|
|
|
|
|
|
|
589
|
|
|
|
|
|
|
inline_size |
590
|
|
|
|
|
|
|
void |
591
|
0
|
|
|
|
|
|
linuxaio_destroy (EV_P) |
592
|
|
|
|
|
|
|
{ |
593
|
0
|
|
|
|
|
|
epoll_destroy (EV_A); |
594
|
0
|
|
|
|
|
|
linuxaio_free_iocbp (EV_A); |
595
|
0
|
|
|
|
|
|
evsys_io_destroy (linuxaio_ctx); /* fails in child, aio context is destroyed */ |
596
|
0
|
|
|
|
|
|
} |
597
|
|
|
|
|
|
|
|
598
|
|
|
|
|
|
|
ecb_cold |
599
|
|
|
|
|
|
|
static void |
600
|
0
|
|
|
|
|
|
linuxaio_fork (EV_P) |
601
|
|
|
|
|
|
|
{ |
602
|
0
|
|
|
|
|
|
linuxaio_submitcnt = 0; /* all pointers were invalidated */ |
603
|
0
|
|
|
|
|
|
linuxaio_free_iocbp (EV_A); /* this frees all iocbs, which is very heavy-handed */ |
604
|
0
|
|
|
|
|
|
evsys_io_destroy (linuxaio_ctx); /* fails in child, aio context is destroyed */ |
605
|
|
|
|
|
|
|
|
606
|
0
|
|
|
|
|
|
linuxaio_iteration = 0; /* we start over in the child */ |
607
|
|
|
|
|
|
|
|
608
|
0
|
0
|
|
|
|
|
while (linuxaio_io_setup (EV_A) < 0) |
609
|
0
|
|
|
|
|
|
ev_syserr ("(libev) linuxaio io_setup"); |
610
|
|
|
|
|
|
|
|
611
|
|
|
|
|
|
|
/* forking epoll should also effectively unregister all fds from the backend */ |
612
|
0
|
|
|
|
|
|
epoll_fork (EV_A); |
613
|
|
|
|
|
|
|
/* epoll_fork already did this. hopefully */ |
614
|
|
|
|
|
|
|
/*fd_rearm_all (EV_A);*/ |
615
|
|
|
|
|
|
|
|
616
|
0
|
|
|
|
|
|
ev_io_stop (EV_A_ &linuxaio_epoll_w); |
617
|
0
|
|
|
|
|
|
ev_io_set (EV_A_ &linuxaio_epoll_w, backend_fd, EV_READ); |
618
|
0
|
|
|
|
|
|
ev_io_start (EV_A_ &linuxaio_epoll_w); |
619
|
0
|
|
|
|
|
|
} |
620
|
|
|
|
|
|
|
|