Date: Tue, 30 Sep 2008 09:51:33 -0500 From: Anthony Liguori <anthony@codemonkey.ws> To: Juergen Lock <nox@jelal.kn-bremen.de> Cc: freebsd-emulation@freebsd.org, qemu-devel@nongnu.org Subject: Re: [Qemu-devel] Re: qemu svn r5281 on FreeBSD - slow usb, vmwarevga, screen updates... (now updated to r5313) Message-ID: <48E23CF5.4000805@codemonkey.ws> In-Reply-To: <200809272252.m8RMq4fu057049@saturn.kn-bremen.de> References: <20080921204025.GA81055@saturn.kn-bremen.de> <cd6b4a5b0809230639x27e94477k315796c2cfb650f2@mail.gmail.com> <200809242210.m8OMAcSZ021572@saturn.kn-bremen.de> <cd6b4a5b0809241954p159dd86u17fdc2a485008e7d@mail.gmail.com> <48DCF9FC.2070708@codemonkey.ws> <20080926220445.GA13099@saturn.kn-bremen.de> <200809272252.m8RMq4fu057049@saturn.kn-bremen.de>
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Juergen Lock wrote:
> In article <48DE5256.5000101@codemonkey.ws> you write:
>
>> [...]
>>
>
>
>>>> The one thing that really tripped me up with the whole aio kld-module
>>>> thing. Perhaps we should detect the presence of the module at run time and
>>>> disable aio? I assume kldload can only be run as root?
>>>>
>>>>
>>> Yes. Atm the ports print a warning when aio is not loaded:
>>>
>>>
>> Yeah, I don't think this is enough. I'd rather see AIO be disabled when
>> modfind("aio") is not available (printing a warning along with that
>> would be fine). A non-privileged user cannot load the aio module so
>> it's not very useful to tell them to load it.
>>
>
> OK so how about the following? (only tested with a raw image, but if
> the way its disabled for OpenBSD works for all of them this should as well.)
>
> Oh and am I right qemu-img doesn't use aio? If it actually does we may
> want to add the same check there instead of just disabling it. (I kept it
> enabled for qemu-nbd since thats not built on FreeBSD anyway.)
>
Disabling aio for everyone is not the right thing if posix-aio is broken.
What would be better is in block-raw-posix.c, to have a one type check
of modfind() (if we're FreeBSD), and if it fails, set a flag that forces
the aio routines to call bdrv_aio_{read,write}_em.
Regards,
Anthony Liguori
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