Replace posix-aio with custom thread pool

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

1 files changed, 3 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index a2a03ec3e2..01f012198b 100644
--- a/Makefile
+++ b/Makefile
@@ -56,6 +56,9 @@ BLOCK_OBJS+=nbd.o block.o aio.o
 ifdef CONFIG_WIN32
 BLOCK_OBJS += block-raw-win32.o
 else
+ifdef CONFIG_AIO
+BLOCK_OBJS += posix-aio-compat.o
+endif
 BLOCK_OBJS += block-raw-posix.o
 endif