Am 17.07.2015 um 16:23 schrieb Stefan Hajnoczi: > raw-posix.c silently ignores BDRV_O_NATIVE_AIO if libaio is unavailable. > It is confusing when aio=native performance is identical to aio=threads > because the binary was accidentally built without libaio. > > Print a deprecation warning if -drive aio=native is used with a binary > that does not support libaio. There are probably users using aio=native > who would be inconvenienced if QEMU suddenly refused to start their > guests. In the future this will become an error. > > Signed-off-by: Stefan Hajnoczi <[email protected]>
had that myself on a freshly installed system without libaio-devel. Acked-by: Christian Borntraeger <[email protected]> Another thing. Would it make sense to change the default to aio=native somewhen? >From what I can tell this seems to outperform aio=threads in most cases. > --- > block/raw-posix.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/block/raw-posix.c b/block/raw-posix.c > index 855febe..e09019c 100644 > --- a/block/raw-posix.c > +++ b/block/raw-posix.c > @@ -519,7 +519,16 @@ static int raw_open_common(BlockDriverState *bs, QDict > *options, > "future QEMU versions.\n", > bs->filename); > } > -#endif > +#else > + if (bdrv_flags & BDRV_O_NATIVE_AIO) { > + error_printf("WARNING: aio=native was specified for '%s', but " > + "is not supported in this build. Falling back to " > + "aio=threads.\n" > + " This will become an error condition in " > + "future QEMU versions.\n", > + bs->filename); > + } > +#endif /* !defined(CONFIG_LINUX_AIO) */ > > s->has_discard = true; > s->has_write_zeroes = true; >
