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Replace posix-aio with custom thread pool

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glibc implements posix-aio as a thread pool and imposes a number of limitations.

1) it limits one request per-file descriptor.  we hack around this by dup()'ing
file descriptors which is hideously ugly

2) it's impossible to add new interfaces and we need a vectored read/write
operation to properly support a zero-copy API.

What has been suggested to me by glibc folks, is to implement whatever new
interfaces we want and then it can eventually be proposed for standardization.
This requires that we implement our own posix-aio implementation though.

This patch implements posix-aio using pthreads.  It immediately eliminates the
need for fd pooling.

It performs at least as well as the current posix-aio code (in some
circumstances, even better).

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5996 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2008-12-12 16:41:40 +00:00
parent 8de2410635
commit 3c529d9359
6 changed files with 287 additions and 106 deletions
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20
configure vendored
View file

@ -149,7 +149,6 @@ FreeBSD)
bsd="yes"
audio_drv_list="oss"
audio_possible_drivers="oss sdl esd pa"
aio_lib="-lpthread"
if [ "$cpu" = "i386" -o "$cpu" = "x86_64" ] ; then
kqemu="yes"
fi
@ -159,7 +158,6 @@ bsd="yes"
audio_drv_list="oss"
audio_possible_drivers="oss sdl esd"
oss_lib="-lossaudio"
aio_lib="-lrt -lpthread"
;;
OpenBSD)
bsd="yes"
@ -167,7 +165,6 @@ openbsd="yes"
audio_drv_list="oss"
audio_possible_drivers="oss sdl esd"
oss_lib="-lossaudio"
aio_lib="-lpthread"
;;
Darwin)
bsd="yes"
@ -178,7 +175,6 @@ audio_drv_list="coreaudio"
audio_possible_drivers="coreaudio sdl fmod"
OS_CFLAGS="-mdynamic-no-pic"
OS_LDFLAGS="-framework CoreFoundation -framework IOKit"
aio_lib="-lpthread"
;;
SunOS)
solaris="yes"
@ -527,15 +523,6 @@ if test "$mingw32" = "yes" ; then
bsd_user="no"
fi
if [ "$darwin" = "yes" -o "$mingw32" = "yes" ] ; then
AIOLIBS=
elif [ "$bsd" = "yes" ]; then
AIOLIBS="$aio_lib"
else
# Some Linux architectures (e.g. s390) don't imply -lpthread automatically.
AIOLIBS="-lrt -lpthread"
fi
if test ! -x "$(which cgcc 2>/dev/null)"; then
sparse="no"
fi
@ -954,14 +941,17 @@ fi
##########################################
# AIO probe
AIOLIBS=""
if test "$aio" = "yes" ; then
aio=no
cat > $TMPC << EOF
#include <aio.h>
int main(void) { return aio_write(NULL); }
#include <pthread.h>
int main(void) { pthread_mutex_t lock; return 0; }
EOF
if $cc $ARCH_CFLAGS -o $TMPE $AIOLIBS $TMPC 2> /dev/null ; then
aio=yes
AIOLIBS="-lpthread"
fi
fi