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Here is a patch to libaio which adds a timeout parameter to
io_queue_run() and removes io_queue_wait(). This makes my
earlier kernel patch to fs/aio.c unnecessary, since I removed
io_queue_wait() which was calling the io_getevents() syscall
with a zero number of events. This keeps the callback interface
in the library and allows a user process to wait for i/o's to
complete if it wants to. I also changed io_queue_run() to
batch up to 8 completions at a time, so it is more efficient.
This requires no kernel changes. I also updated the io_queue_run()
man page and that is in a separate patch.
Thoughts?
Daniel McNeil <daniel@osdl.org
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diff -rupN -X /home/daniel_nfs/dontdiff libaio-0.3.93/src/io_queue_run.c li=
baio-0.3.93-io_queue_run_with_timeout/src/io_queue_run.c
--- libaio-0.3.93/src/io_queue_run.c 2002-09-26 09:39:38.000000000 -0700
+++ libaio-0.3.93-io_queue_run_with_timeout/src/io_queue_run.c 2003-07-08 1=
6:38:52.983739711 -0700
@@ -21,19 +21,33 @@
#include <stdlib.h>
#include <time.h>
=20
-int io_queue_run(io_context_t ctx)
+#define IO_BATCH_EVENTS 8 /* number of events to batch up */
+
+int io_queue_run(io_context_t ctx, struct timespec *timeout)
{
- static struct timespec timeout =3D { 0, 0 };
- struct io_event event;
- int ret;
-
- /* FIXME: batch requests? */
- while (1 =3D=3D (ret =3D io_getevents(ctx, 0, 1, &event, &timeout))) {
- io_callback_t cb =3D (io_callback_t)event.data;
- struct iocb *iocb =3D event.obj;
+ struct io_event events[IO_BATCH_EVENTS];
+ struct io_event *ep;
+ int ret =3D 0; /* total number of events processed */
+ int n;
+
+ /*
+ * Process io events and call the callbacks.
+ * Try to batch the events up to IO_BATCH_EVENTS at a time.
+ * Loop until we have read all the available events and called the callba=
cks.
+ */
+ do {
+ int i;
+
+ if ((n =3D io_getevents(ctx, 1, IO_BATCH_EVENTS, &events, timeout)) <=3D=
0)
+ break;
+ ret +=3D n;
+ for (ep =3D events, i =3D n; i-- > 0; ep++) {
+ io_callback_t cb =3D (io_callback_t)ep->data;
+ struct iocb *iocb =3D ep->obj;
=20
- cb(ctx, iocb, event.res, event.res2);
- }
+ cb(ctx, iocb, ep->res, ep->res2);
+ }
+ } while (n =3D=3D IO_BATCH_EVENTS);
=20
- return ret;
+ return ret ? ret : n; /* return number of events or error */
}
diff -rupN -X /home/daniel_nfs/dontdiff libaio-0.3.93/src/libaio.h libaio-0=
.3.93-io_queue_run_with_timeout/src/libaio.h
--- libaio-0.3.93/src/libaio.h 2002-10-08 16:33:42.000000000 -0700
+++ libaio-0.3.93-io_queue_run_with_timeout/src/libaio.h 2003-07-08 16:41:0=
6.471880979 -0700
@@ -123,7 +123,7 @@ extern int io_queue_init(int maxevents,=20
/*extern int io_queue_grow(io_context_t ctx, int new_maxevents);*/
extern int io_queue_release(io_context_t ctx);
/*extern int io_queue_wait(io_context_t ctx, struct timespec *timeout);*/
-extern int io_queue_run(io_context_t ctx);
+extern int io_queue_run(io_context_t ctx, struct timespec *timeout);
=20
/* Actual syscalls */
extern int io_setup(int maxevents, io_context_t *ctxp);
Binary files libaio-0.3.93/src/libaio.so.1 and libaio-0.3.93-io_queue_run_w=
ith_timeout/src/libaio.so.1 differ
diff -rupN -X /home/daniel_nfs/dontdiff libaio-0.3.93/src/Makefile libaio-0=
.3.93-io_queue_run_with_timeout/src/Makefile
--- libaio-0.3.93/src/Makefile 2002-09-12 20:30:12.000000000 -0700
+++ libaio-0.3.93-io_queue_run_with_timeout/src/Makefile 2003-07-08 16:47:2=
9.426559122 -0700
@@ -14,7 +14,7 @@ all: $(all_targets)
=20
# libaio provided functions
libaio_srcs :=3D io_queue_init.c io_queue_release.c
-libaio_srcs +=3D io_queue_wait.c io_queue_run.c
+libaio_srcs +=3D io_queue_run.c
=20
# real syscalls
libaio_srcs +=3D io_getevents.c io_submit.c io_cancel.c
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diff -rupN -X /home/daniel_nfs/dontdiff libaio-0.3.93/man/io_queue_run.3 li=
baio-0.3.93-io_queue_run_with_timeout/man/io_queue_run.3
--- libaio-0.3.93/man/io_queue_run.3 2002-09-26 08:55:18.000000000 -0700
+++ libaio-0.3.93-io_queue_run_with_timeout/man/io_queue_run.3 2003-07-08 1=
7:28:55.441862077 -0700
@@ -9,16 +9,21 @@ io_queue_run \- Handle completed io requ
.B #include <libaio.h>
.br
.sp
-.BI "int io_queue_run(io_context_t ctx );"
+.BI "int io_queue_run(io_context_t ctx, struct timespec *timeout);"
.sp
.fi
.SH DESCRIPTION
.B io_queue_run
-Attempts to read all the events events from
-the completion queue for the aio_context specified by ctx_id.
+Attempts to read all the events events from
+the completion queue for the aio_context specified by ctx and calls the ca=
llbacks
+setup by io_set_callback().
.SH "RETURN VALUES"
+Returns the number of events handled.
May return
-0 if no events are available.
+0 if no events are available and the timeout specified
+by timeout has elapsed, where timeout =3D=3D NULL specifies an infinite
+timeout. Note that the timeout pointed to by timeout is relative and
+will be updated if not NULL and the operation blocks.
Will fail with -ENOSYS if not implemented.
.SH ERRORS
.TP
@@ -44,7 +49,6 @@ Not implemented
.BR io_prep_pwrite(3),
.BR io_queue_init(3),
.BR io_queue_release(3),
-.BR io_queue_wait(3),
.BR io_set_callback(3),
.BR io_submit(3),
.BR errno(3)
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