d37c975fb1
AIO control blocks are frequently acquired and released because each aio request involves at least one AIOCB. Therefore, we pool them to avoid heap allocation overhead. The problem with the freelist approach in AIOPool is thread-safety. If we want BlockDriverStates to associate with AioContexts that execute in multiple threads, then a global freelist becomes a problem. This patch drops the freelist and instead uses g_slice_alloc() which is tuned for per-thread fixed-size object pools. qemu_aio_get() and qemu_aio_release() are now thread-safe. Note that the change from g_malloc0() to g_slice_alloc() should be safe since the freelist reuse case doesn't zero the AIOCB either. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Read the documentation in qemu-doc.html or on http://wiki.qemu.org - QEMU team