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root |
1.1 |
/* |
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* libev linux aio fd activity backend |
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* |
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* Copyright (c) 2019 Marc Alexander Lehmann <libev@schmorp.de> |
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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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root |
1.25 |
/* |
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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 initialiasing 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 |
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* of event handling we have to switch to 100% epoll polling. and |
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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 trainwreck: 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 thats not counting |
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* the fact that this backend also depends on the epoll backend, making |
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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 whwetaver linux does is far, far far worse. |
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*/ |
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root |
1.10 |
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root |
1.1 |
#include <sys/time.h> /* actually linux/time.h, but we must assume they are compatible */ |
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root |
1.2 |
#include <poll.h> |
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root |
1.1 |
#include <linux/aio_abi.h> |
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/*****************************************************************************/ |
92 |
root |
1.25 |
/* syscall wrapdadoop - this section has the raw api/abi definitions */ |
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root |
1.1 |
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#include <sys/syscall.h> /* no glibc wrappers */ |
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root |
1.5 |
/* aio_abi.h is not versioned in any way, so we cannot test for its existance */ |
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root |
1.1 |
#define IOCB_CMD_POLL 5 |
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root |
1.25 |
/* 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 |
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* can tell you what the future semantics of compat_features and |
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* incompat_features are, or what header_length actually is for. |
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*/ |
104 |
root |
1.1 |
#define AIO_RING_MAGIC 0xa10a10a1 |
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#define AIO_RING_INCOMPAT_FEATURES 0 |
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struct aio_ring |
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{ |
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unsigned id; /* kernel internal index number */ |
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unsigned nr; /* number of io_events */ |
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unsigned head; /* Written to by userland or by kernel. */ |
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unsigned tail; |
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unsigned magic; |
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unsigned compat_features; |
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unsigned incompat_features; |
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unsigned header_length; /* size of aio_ring */ |
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struct io_event io_events[0]; |
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}; |
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121 |
root |
1.6 |
inline_size |
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int |
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root |
1.20 |
evsys_io_setup (unsigned nr_events, aio_context_t *ctx_idp) |
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root |
1.1 |
{ |
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return syscall (SYS_io_setup, nr_events, ctx_idp); |
126 |
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} |
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128 |
root |
1.6 |
inline_size |
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int |
130 |
root |
1.20 |
evsys_io_destroy (aio_context_t ctx_id) |
131 |
root |
1.1 |
{ |
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return syscall (SYS_io_destroy, ctx_id); |
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} |
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135 |
root |
1.6 |
inline_size |
136 |
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int |
137 |
root |
1.20 |
evsys_io_submit (aio_context_t ctx_id, long nr, struct iocb *cbp[]) |
138 |
root |
1.1 |
{ |
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return syscall (SYS_io_submit, ctx_id, nr, cbp); |
140 |
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} |
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142 |
root |
1.6 |
inline_size |
143 |
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int |
144 |
root |
1.20 |
evsys_io_cancel (aio_context_t ctx_id, struct iocb *cbp, struct io_event *result) |
145 |
root |
1.1 |
{ |
146 |
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return syscall (SYS_io_cancel, ctx_id, cbp, result); |
147 |
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} |
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149 |
root |
1.6 |
inline_size |
150 |
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int |
151 |
root |
1.20 |
evsys_io_getevents (aio_context_t ctx_id, long min_nr, long nr, struct io_event *events, struct timespec *timeout) |
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root |
1.1 |
{ |
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return syscall (SYS_io_getevents, ctx_id, min_nr, nr, events, timeout); |
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} |
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/*****************************************************************************/ |
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/* actual backed implementation */ |
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159 |
root |
1.25 |
ecb_cold |
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static int |
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linuxaio_nr_events (EV_P) |
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{ |
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/* we start with 16 iocbs and incraese from there |
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* that's tiny, but the kernel has a rather low system-wide |
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* limit that can be reached quickly, so let's be parsimonious |
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* with this resource. |
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* Rest assured, the kernel generously rounds up small and big numbers |
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* in different ways (but doesn't seem to charge you for it). |
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* The 15 here is because the kernel usually has a power of two as aio-max-nr, |
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* and this helps to take advantage of that limit. |
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*/ |
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/* we try to fill 4kB pages exactly. |
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* the ring buffer header is 32 bytes, every io event is 32 bytes. |
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* the kernel takes the io requests number, doubles it, adds 2 |
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* and adds the ring buffer. |
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* the way we use this is by starting low, and then roughly doubling the |
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* size each time we hit a limit. |
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*/ |
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int requests = 15 << linuxaio_iteration; |
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int one_page = (4096 |
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/ sizeof (struct io_event) ) / 2; /* how many fit into one page */ |
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int first_page = ((4096 - sizeof (struct aio_ring)) |
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/ sizeof (struct io_event) - 2) / 2; /* how many fit into the first page */ |
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/* if everything fits into one page, use count exactly */ |
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if (requests > first_page) |
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/* otherwise, round down to full pages and add the first page */ |
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requests = requests / one_page * one_page + first_page; |
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return requests; |
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} |
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root |
1.7 |
/* we use out own wrapper structure in acse we ever want to do something "clever" */ |
196 |
root |
1.1 |
typedef struct aniocb |
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{ |
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struct iocb io; |
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/*int inuse;*/ |
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} *ANIOCBP; |
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202 |
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inline_size |
203 |
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void |
204 |
root |
1.22 |
linuxaio_array_needsize_iocbp (ANIOCBP *base, int offset, int count) |
205 |
root |
1.1 |
{ |
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while (count--) |
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{ |
208 |
root |
1.23 |
/* TODO: quite the overhead to allocate every iocb separately, maybe use our own alocator? */ |
209 |
root |
1.22 |
ANIOCBP iocb = (ANIOCBP)ev_malloc (sizeof (*iocb)); |
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211 |
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/* full zero initialise is probably not required at the moment, but |
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* this is not well documented, so we better do it. |
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*/ |
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memset (iocb, 0, sizeof (*iocb)); |
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iocb->io.aio_lio_opcode = IOCB_CMD_POLL; |
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iocb->io.aio_data = offset; |
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iocb->io.aio_fildes = offset; |
219 |
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220 |
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base [offset++] = iocb; |
221 |
root |
1.1 |
} |
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} |
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224 |
root |
1.6 |
ecb_cold |
225 |
root |
1.1 |
static void |
226 |
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linuxaio_free_iocbp (EV_P) |
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{ |
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while (linuxaio_iocbpmax--) |
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ev_free (linuxaio_iocbps [linuxaio_iocbpmax]); |
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231 |
root |
1.6 |
linuxaio_iocbpmax = 0; /* next resize will completely reallocate the array, at some overhead */ |
232 |
root |
1.1 |
} |
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static void |
235 |
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linuxaio_modify (EV_P_ int fd, int oev, int nev) |
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{ |
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array_needsize (ANIOCBP, linuxaio_iocbps, linuxaio_iocbpmax, fd + 1, linuxaio_array_needsize_iocbp); |
238 |
root |
1.22 |
ANIOCBP iocb = linuxaio_iocbps [fd]; |
239 |
root |
1.1 |
|
240 |
root |
1.10 |
if (iocb->io.aio_reqprio < 0) |
241 |
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{ |
242 |
root |
1.25 |
/* we handed this fd over to epoll, so undo this first */ |
243 |
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/* we do it manually becvause the optimisations on epoll_modfy won't do us any good */ |
244 |
root |
1.10 |
epoll_ctl (backend_fd, EPOLL_CTL_DEL, fd, 0); |
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iocb->io.aio_reqprio = 0; |
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} |
247 |
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248 |
root |
1.1 |
if (iocb->io.aio_buf) |
249 |
root |
1.25 |
/* io_cancel always returns some error on relevant kernels, but works */ |
250 |
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evsys_io_cancel (linuxaio_ctx, &iocb->io, (struct io_event *)0); |
251 |
root |
1.1 |
|
252 |
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if (nev) |
253 |
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{ |
254 |
root |
1.22 |
iocb->io.aio_buf = |
255 |
root |
1.1 |
(nev & EV_READ ? POLLIN : 0) |
256 |
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| (nev & EV_WRITE ? POLLOUT : 0); |
257 |
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258 |
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/* queue iocb up for io_submit */ |
259 |
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/* this assumes we only ever get one call per fd per loop iteration */ |
260 |
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++linuxaio_submitcnt; |
261 |
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array_needsize (struct iocb *, linuxaio_submits, linuxaio_submitmax, linuxaio_submitcnt, array_needsize_noinit); |
262 |
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linuxaio_submits [linuxaio_submitcnt - 1] = &iocb->io; |
263 |
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} |
264 |
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} |
265 |
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266 |
root |
1.19 |
static void |
267 |
root |
1.25 |
linuxaio_epoll_cb (EV_P_ struct ev_io *w, int revents) |
268 |
root |
1.19 |
{ |
269 |
root |
1.25 |
epoll_poll (EV_A_ 0); |
270 |
root |
1.19 |
} |
271 |
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272 |
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static void |
273 |
root |
1.25 |
linuxaio_fd_rearm (EV_P_ int fd) |
274 |
root |
1.19 |
{ |
275 |
root |
1.25 |
anfds [fd].events = 0; |
276 |
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linuxaio_iocbps [fd]->io.aio_buf = 0; |
277 |
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fd_change (EV_A_ fd, EV_ANFD_REIFY); |
278 |
root |
1.19 |
} |
279 |
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280 |
root |
1.1 |
static void |
281 |
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linuxaio_parse_events (EV_P_ struct io_event *ev, int nr) |
282 |
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{ |
283 |
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while (nr) |
284 |
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{ |
285 |
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int fd = ev->data; |
286 |
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int res = ev->res; |
287 |
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|
288 |
root |
1.2 |
assert (("libev: iocb fd must be in-bounds", fd >= 0 && fd < anfdmax)); |
289 |
root |
1.1 |
|
290 |
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/* feed events, we do not expect or handle POLLNVAL */ |
291 |
root |
1.21 |
fd_event ( |
292 |
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EV_A_ |
293 |
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fd, |
294 |
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(res & (POLLOUT | POLLERR | POLLHUP) ? EV_WRITE : 0) |
295 |
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| (res & (POLLIN | POLLERR | POLLHUP) ? EV_READ : 0) |
296 |
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); |
297 |
root |
1.1 |
|
298 |
root |
1.25 |
/* linux aio is oneshot: rearm fd. TODO: this does more work than needed */ |
299 |
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linuxaio_fd_rearm (EV_A_ fd); |
300 |
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301 |
root |
1.1 |
--nr; |
302 |
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++ev; |
303 |
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} |
304 |
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} |
305 |
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306 |
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/* get any events from ringbuffer, return true if any were handled */ |
307 |
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static int |
308 |
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linuxaio_get_events_from_ring (EV_P) |
309 |
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{ |
310 |
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struct aio_ring *ring = (struct aio_ring *)linuxaio_ctx; |
311 |
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|
312 |
root |
1.13 |
/* the kernel reads and writes both of these variables, */ |
313 |
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/* as a C extension, we assume that volatile use here */ |
314 |
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/* both makes reads atomic and once-only */ |
315 |
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unsigned head = *(volatile unsigned *)&ring->head; |
316 |
root |
1.1 |
unsigned tail = *(volatile unsigned *)&ring->tail; |
317 |
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318 |
root |
1.6 |
if (head == tail) |
319 |
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return 0; |
320 |
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|
321 |
root |
1.7 |
/* bail out if the ring buffer doesn't match the expected layout */ |
322 |
root |
1.17 |
if (expect_false (ring->magic != AIO_RING_MAGIC) |
323 |
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|| ring->incompat_features != AIO_RING_INCOMPAT_FEATURES |
324 |
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|| ring->header_length != sizeof (struct aio_ring)) /* TODO: or use it to find io_event[0]? */ |
325 |
root |
1.1 |
return 0; |
326 |
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|
327 |
root |
1.12 |
/* make sure the events up to tail are visible */ |
328 |
root |
1.9 |
ECB_MEMORY_FENCE_ACQUIRE; |
329 |
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|
330 |
root |
1.1 |
/* parse all available events, but only once, to avoid starvation */ |
331 |
|
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if (tail > head) /* normal case around */ |
332 |
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linuxaio_parse_events (EV_A_ ring->io_events + head, tail - head); |
333 |
root |
1.6 |
else /* wrapped around */ |
334 |
root |
1.1 |
{ |
335 |
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linuxaio_parse_events (EV_A_ ring->io_events + head, ring->nr - head); |
336 |
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linuxaio_parse_events (EV_A_ ring->io_events, tail); |
337 |
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} |
338 |
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|
339 |
root |
1.24 |
ECB_MEMORY_FENCE_RELAXED; |
340 |
root |
1.16 |
/* as an extension to C, we hope that the volatile will make this atomic and once-only */ |
341 |
root |
1.11 |
*(volatile unsigned *)&ring->head = tail; |
342 |
root |
1.12 |
/* make sure kernel can see our new head value - probably not required */ |
343 |
root |
1.11 |
ECB_MEMORY_FENCE_RELEASE; |
344 |
root |
1.1 |
|
345 |
|
|
return 1; |
346 |
|
|
} |
347 |
|
|
|
348 |
|
|
/* read at least one event from kernel, or timeout */ |
349 |
|
|
inline_size |
350 |
|
|
void |
351 |
|
|
linuxaio_get_events (EV_P_ ev_tstamp timeout) |
352 |
|
|
{ |
353 |
|
|
struct timespec ts; |
354 |
root |
1.18 |
struct io_event ioev[1]; |
355 |
root |
1.1 |
int res; |
356 |
|
|
|
357 |
|
|
if (linuxaio_get_events_from_ring (EV_A)) |
358 |
|
|
return; |
359 |
|
|
|
360 |
|
|
/* no events, so wait for at least one, then poll ring buffer again */ |
361 |
root |
1.7 |
/* this degrades to one event per loop iteration */ |
362 |
root |
1.1 |
/* if the ring buffer changes layout, but so be it */ |
363 |
|
|
|
364 |
root |
1.19 |
EV_RELEASE_CB; |
365 |
|
|
|
366 |
root |
1.1 |
ts.tv_sec = (long)timeout; |
367 |
|
|
ts.tv_nsec = (long)((timeout - ts.tv_sec) * 1e9); |
368 |
|
|
|
369 |
root |
1.20 |
res = evsys_io_getevents (linuxaio_ctx, 1, sizeof (ioev) / sizeof (ioev [0]), ioev, &ts); |
370 |
root |
1.1 |
|
371 |
root |
1.19 |
EV_ACQUIRE_CB; |
372 |
|
|
|
373 |
root |
1.1 |
if (res < 0) |
374 |
root |
1.10 |
if (errno == EINTR) |
375 |
|
|
/* ignored */; |
376 |
|
|
else |
377 |
|
|
ev_syserr ("(libev) linuxaio io_getevents"); |
378 |
root |
1.1 |
else if (res) |
379 |
|
|
{ |
380 |
|
|
/* at least one event received, handle it and any remaining ones in the ring buffer */ |
381 |
root |
1.18 |
linuxaio_parse_events (EV_A_ ioev, res); |
382 |
root |
1.1 |
linuxaio_get_events_from_ring (EV_A); |
383 |
|
|
} |
384 |
|
|
} |
385 |
|
|
|
386 |
root |
1.25 |
static int |
387 |
|
|
linuxaio_io_setup (EV_P) |
388 |
|
|
{ |
389 |
|
|
linuxaio_ctx = 0; |
390 |
|
|
return evsys_io_setup (linuxaio_nr_events (EV_A), &linuxaio_ctx); |
391 |
|
|
} |
392 |
|
|
|
393 |
root |
1.1 |
static void |
394 |
|
|
linuxaio_poll (EV_P_ ev_tstamp timeout) |
395 |
|
|
{ |
396 |
|
|
int submitted; |
397 |
|
|
|
398 |
|
|
/* first phase: submit new iocbs */ |
399 |
|
|
|
400 |
|
|
/* io_submit might return less than the requested number of iocbs */ |
401 |
|
|
/* this is, afaics, only because of errors, but we go by the book and use a loop, */ |
402 |
|
|
/* which allows us to pinpoint the errornous iocb */ |
403 |
|
|
for (submitted = 0; submitted < linuxaio_submitcnt; ) |
404 |
|
|
{ |
405 |
root |
1.20 |
int res = evsys_io_submit (linuxaio_ctx, linuxaio_submitcnt - submitted, linuxaio_submits + submitted); |
406 |
root |
1.1 |
|
407 |
root |
1.17 |
if (expect_false (res < 0)) |
408 |
root |
1.25 |
if (errno == EINVAL) |
409 |
root |
1.10 |
{ |
410 |
root |
1.15 |
/* This happens for unsupported fds, officially, but in my testing, |
411 |
root |
1.10 |
* also randomly happens for supported fds. We fall back to good old |
412 |
|
|
* poll() here, under the assumption that this is a very rare case. |
413 |
root |
1.19 |
* See https://lore.kernel.org/patchwork/patch/1047453/ to see |
414 |
|
|
* discussion about such a case (ttys) where polling for POLLIN |
415 |
|
|
* fails but POLLIN|POLLOUT works. |
416 |
root |
1.10 |
*/ |
417 |
|
|
struct iocb *iocb = linuxaio_submits [submitted]; |
418 |
root |
1.25 |
epoll_modify (EV_A_ iocb->aio_fildes, 0, anfds [iocb->aio_fildes].events); |
419 |
|
|
iocb->aio_reqprio = -1; /* mark iocb as epoll */ |
420 |
root |
1.10 |
|
421 |
root |
1.25 |
res = 1; /* skip this iocb - another iocb, another chance */ |
422 |
|
|
} |
423 |
|
|
else if (errno == EAGAIN) |
424 |
|
|
{ |
425 |
|
|
/* This happens when the ring buffer is full, or some other shit we |
426 |
|
|
* dont' know and isn't documented. Most likely because we have too |
427 |
|
|
* many requests and linux aio can't be assed to handle them. |
428 |
|
|
* In this case, we try to allocate a larger ring buffer, freeing |
429 |
|
|
* ours first. This might fail, in which case we have to fall back to 100% |
430 |
|
|
* epoll. |
431 |
|
|
* God, how I hate linux not getting its act together. Ever. |
432 |
|
|
*/ |
433 |
|
|
evsys_io_destroy (linuxaio_ctx); |
434 |
|
|
linuxaio_submitcnt = 0; |
435 |
|
|
|
436 |
|
|
/* rearm all fds with active iocbs */ |
437 |
|
|
{ |
438 |
|
|
int fd; |
439 |
|
|
for (fd = 0; fd < linuxaio_iocbpmax; ++fd) |
440 |
|
|
if (linuxaio_iocbps [fd]->io.aio_buf) |
441 |
|
|
linuxaio_fd_rearm (EV_A_ fd); |
442 |
|
|
} |
443 |
|
|
|
444 |
|
|
++linuxaio_iteration; |
445 |
|
|
if (linuxaio_io_setup (EV_A) < 0) |
446 |
|
|
{ |
447 |
|
|
/* to bad, we can't get a new aio context, go 100% epoll */ |
448 |
|
|
linuxaio_free_iocbp (EV_A); |
449 |
|
|
ev_io_stop (EV_A_ &linuxaio_epoll_w); |
450 |
|
|
ev_ref (EV_A); |
451 |
|
|
linuxaio_ctx = 0; |
452 |
|
|
backend_modify = epoll_modify; |
453 |
|
|
backend_poll = epoll_poll; |
454 |
|
|
} |
455 |
root |
1.21 |
|
456 |
root |
1.25 |
timeout = 0; |
457 |
|
|
/* it's easiest to handle this mess in another iteration */ |
458 |
|
|
return; |
459 |
root |
1.10 |
} |
460 |
root |
1.21 |
else if (errno == EBADF) |
461 |
|
|
{ |
462 |
|
|
fd_kill (EV_A_ linuxaio_submits [submitted]->aio_fildes); |
463 |
|
|
|
464 |
|
|
res = 1; /* skip this iocb */ |
465 |
|
|
} |
466 |
root |
1.1 |
else |
467 |
root |
1.8 |
ev_syserr ("(libev) linuxaio io_submit"); |
468 |
root |
1.1 |
|
469 |
|
|
submitted += res; |
470 |
|
|
} |
471 |
|
|
|
472 |
|
|
linuxaio_submitcnt = 0; |
473 |
|
|
|
474 |
|
|
/* second phase: fetch and parse events */ |
475 |
|
|
|
476 |
|
|
linuxaio_get_events (EV_A_ timeout); |
477 |
|
|
} |
478 |
|
|
|
479 |
|
|
inline_size |
480 |
|
|
int |
481 |
|
|
linuxaio_init (EV_P_ int flags) |
482 |
|
|
{ |
483 |
|
|
/* would be great to have a nice test for IOCB_CMD_POLL instead */ |
484 |
root |
1.2 |
/* also: test some semi-common fd types, such as files and ttys in recommended_backends */ |
485 |
root |
1.25 |
/* 4.18 introduced IOCB_CMD_POLL, 4.19 made epoll work */ |
486 |
root |
1.15 |
if (ev_linux_version () < 0x041300) |
487 |
|
|
return 0; |
488 |
root |
1.25 |
|
489 |
|
|
if (!epoll_init (EV_A_ 0)) |
490 |
root |
1.1 |
return 0; |
491 |
|
|
|
492 |
root |
1.25 |
linuxaio_iteration = 0; |
493 |
root |
1.1 |
|
494 |
root |
1.25 |
if (linuxaio_io_setup (EV_A) < 0) |
495 |
root |
1.10 |
{ |
496 |
root |
1.25 |
epoll_destroy (EV_A); |
497 |
root |
1.10 |
return 0; |
498 |
|
|
} |
499 |
|
|
|
500 |
|
|
ev_io_init (EV_A_ &linuxaio_epoll_w, linuxaio_epoll_cb, backend_fd, EV_READ); |
501 |
root |
1.19 |
ev_set_priority (&linuxaio_epoll_w, EV_MAXPRI); |
502 |
root |
1.10 |
ev_io_start (EV_A_ &linuxaio_epoll_w); |
503 |
root |
1.14 |
ev_unref (EV_A); /* watcher should not keep loop alive */ |
504 |
root |
1.10 |
|
505 |
root |
1.1 |
backend_modify = linuxaio_modify; |
506 |
|
|
backend_poll = linuxaio_poll; |
507 |
|
|
|
508 |
|
|
linuxaio_iocbpmax = 0; |
509 |
|
|
linuxaio_iocbps = 0; |
510 |
|
|
|
511 |
|
|
linuxaio_submits = 0; |
512 |
|
|
linuxaio_submitmax = 0; |
513 |
|
|
linuxaio_submitcnt = 0; |
514 |
|
|
|
515 |
|
|
return EVBACKEND_LINUXAIO; |
516 |
|
|
} |
517 |
|
|
|
518 |
|
|
inline_size |
519 |
|
|
void |
520 |
|
|
linuxaio_destroy (EV_P) |
521 |
|
|
{ |
522 |
root |
1.25 |
epoll_destroy (EV_A); |
523 |
root |
1.1 |
linuxaio_free_iocbp (EV_A); |
524 |
root |
1.21 |
evsys_io_destroy (linuxaio_ctx); |
525 |
root |
1.1 |
} |
526 |
|
|
|
527 |
|
|
inline_size |
528 |
|
|
void |
529 |
|
|
linuxaio_fork (EV_P) |
530 |
|
|
{ |
531 |
root |
1.6 |
/* this frees all iocbs, which is very heavy-handed */ |
532 |
root |
1.2 |
linuxaio_destroy (EV_A); |
533 |
root |
1.6 |
linuxaio_submitcnt = 0; /* all pointers were invalidated */ |
534 |
root |
1.2 |
|
535 |
root |
1.25 |
linuxaio_iteration = 0; /* we start over in the child */ |
536 |
|
|
|
537 |
|
|
while (linuxaio_io_setup (EV_A) < 0) |
538 |
root |
1.8 |
ev_syserr ("(libev) linuxaio io_setup"); |
539 |
root |
1.2 |
|
540 |
root |
1.25 |
epoll_fork (EV_A); |
541 |
root |
1.10 |
|
542 |
|
|
ev_io_stop (EV_A_ &linuxaio_epoll_w); |
543 |
root |
1.25 |
ev_io_set (EV_A_ &linuxaio_epoll_w, backend_fd, EV_READ); |
544 |
root |
1.10 |
ev_io_start (EV_A_ &linuxaio_epoll_w); |
545 |
|
|
|
546 |
root |
1.25 |
/* epoll_fork already did this. hopefully */ |
547 |
|
|
/*fd_rearm_all (EV_A);*/ |
548 |
root |
1.1 |
} |
549 |
|
|
|