On Tue, Sep 25, 2012 at 02:55:46PM +0200, Paolo Bonzini wrote: > This series removes the globals from async.c/aio-posix.c so that > multiple AIO contexts (mini event loops) can be added. Right now, > all block devices still use qemu_bh_new, but switching them to > aio_bh_new would let you associate different files with different > AIO contexts. > > As an added bonus, integration with the glib main loop now happens > via GSource. Each AIO context is a GSource, which means you can > choose either to run it in its own thread (this of course needs > proper locking which is not yet here), or to attach it to the main > thread. > > In this state this is a bit of an academic exercise (though it works > and may even make sense for 1.3), but I think it's an example of the > tiny steps that can lead us towards an upstreamable version of the > data-plane code. > > Paolo > > Paolo Bonzini (17): > build: do not rely on indirect inclusion of qemu-config.h > event_notifier: enable it to use pipes > event_notifier: add Win32 implementation > aio: change qemu_aio_set_fd_handler to return void > aio: provide platform-independent API > aio: introduce AioContext, move bottom halves there > aio: add I/O handlers to the AioContext interface > aio: add non-blocking variant of aio_wait > aio: prepare for introducing GSource-based dispatch > aio: add Win32 implementation > aio: make AioContexts GSources > aio: add aio_notify > aio: call aio_notify after setting I/O handlers > main-loop: use GSource to poll AIO file descriptors > main-loop: use aio_notify for qemu_notify_event > aio: clean up now-unused functions > linux-aio: use event notifiers > > Makefile.objs | 6 +- > aio.c => aio-posix.c | 159 +++++++++++++++------- > aio.c => aio-win32.c | 190 ++++++++++++++------------ > async.c | 118 ++++++++++++++--- > block/Makefile.objs | 6 +- > block/blkdebug.c | 1 + > block/iscsi.c | 1 + > event_notifier.c => event_notifier-posix.c | 83 +++++++++--- > event_notifier.c => event_notifier-win32.c | 48 +++---- > event_notifier.h | 20 ++- > hw/hw.h | 1 + > iohandler.c | 1 + > linux-aio.c | 49 +++---- > main-loop.c | 152 +++++++-------------- > main-loop.h | 56 +------- > oslib-posix.c | 31 ----- > qemu-aio.h | 206 > +++++++++++++++++++++++++++-- > qemu-char.h | 1 + > qemu-common.h | 2 +- > qemu-config.h | 1 + > qemu-coroutine-lock.c | 2 +- > qemu-os-win32.h | 1 - > 22 file modificati, 702 inserzioni(+), 433 rimozioni(-) > copy aio.c => aio-posix.c (48%) > rename aio.c => aio-win32.c (44%) > copy event_notifier.c => event_notifier-posix.c (36%) > rename event_notifier.c => event_notifier-win32.c (49%)
This series looks useful - it compartmentalizes aio.c so there can be multiple event loops. In order to get a performance benefit (hooking up virtio-blk ioeventfd to a non-QEMU mutex thread) we need two more things: 1. Block layer association with an AioContext (perhaps BlockDriverState <-> AioContext attaching). 2. Thread pool for dispatching I/O requests outside the QEMU global mutex. I'm starting to work on these steps and will send RFCs. This series looks good to me. Stefan
