Re: [libvirt] [PATCH libvirt] qemu: show a warning when using aio=native without cache=none

Qemu will fallback to aio=threads when the cache mode doesn't use O_DIRECT, even if aio=native was explictly set. Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1086704 Signed-off-by: Giuseppe Scrivano <gscrivan(a)redhat.com&gt; --- src/qemu/qemu_command.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index fb64cda..92a6c9a 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -3477,6 +3477,13 @@ qemuBuildDriveStr(virConnectPtr conn, mode = qemuDiskCacheV1TypeToString(disk->cachemode); } + if (disk->iomode == VIR_DOMAIN_DISK_IO_NATIVE && + disk->cachemode != VIR_DOMAIN_DISK_CACHE_DIRECTSYNC) { + VIR_WARN("native I/O needs either no disk cache " + "or directsync cache mode, QEMU will fallback " + "to aio=threads"); + }