Date: Thu, 7 Apr 2016 17:57:46 +0100 From: Matthew Seaman <matthew@FreeBSD.org> To: freebsd-questions@freebsd.org Subject: Re: AIO in 10.0-RELEASE Message-ID: <5706918A.2060502@FreeBSD.org> In-Reply-To: <CAHzLAVHKiC3%2BaMDq1JyzNx%2B3eer765PJc-Zrhm=ZKPBn_OJBBw@mail.gmail.com> References: <CAHzLAVHKiC3%2BaMDq1JyzNx%2B3eer765PJc-Zrhm=ZKPBn_OJBBw@mail.gmail.com>
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From: Matthew Seaman <matthew@FreeBSD.org>
To: freebsd-questions@freebsd.org
Message-ID: <5706918A.2060502@FreeBSD.org>
Subject: Re: AIO in 10.0-RELEASE
References: <CAHzLAVHKiC3+aMDq1JyzNx+3eer765PJc-Zrhm=ZKPBn_OJBBw@mail.gmail.com>
In-Reply-To: <CAHzLAVHKiC3+aMDq1JyzNx+3eer765PJc-Zrhm=ZKPBn_OJBBw@mail.gmail.com>
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On 2016/04/07 16:25, Rick Miller wrote:
> Hi all,
>=20
> A user has been implementing AIO features in an application. They asse=
rt
> that, despite aio(4) stating that it is enabled either statically (with=
> VFS_AIO in the kernel config) or dynamically (kldload), in their
> development environment there was no requirement for either of these
> methods of enabling AIO. My google-foo is failing me when it comes to
> FreeBSD's AIO.
>=20
> This question defies logic, but is it possible that AIO works by defaul=
t in
> earlier versions of 10.0 and not in more recent version of 10.0 without=
any
> local system changes?
>=20
You asked a pretty similar question last month, where one of the replies
pointed you to this in the UPDATING file:
20160301:
The AIO subsystem is now a standard part of the kernel. The
VFS_AIO kernel option and aio.ko kernel module have been removed.=
Due to stability concerns, asynchronous I/O requests are only
permitted on sockets and raw disks by default. To enable
asynchronous I/O requests on all file types, set the
vfs.aio.enable_unsafe sysctl to a non-zero value.
In fact, that change was *after* 10.3 was branched, so 10.3-RELEASE
should behave the same as 10.2 and earlier as far as AIO is concerned.
https://svnweb.freebsd.org/base/releng/10.3/UPDATING?revision=3D297262&vi=
ew=3Dmarkup
As far as I can tell from the manual, calls to aio_read(2) and similar
functions should generate an ENOSYS error code, unless your system
kernel has the aio module ceither compiled in or loaded. Which runs
counter to your user's experience.
I suggest asking on freebsd-hackers@... as you're more likely to come to
the attention of the responsible developers there.
Cheers,
Matthew
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