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From: Leon Woestenberg <leon.woestenberg@gmail.com>
To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	devel@driverdev.osuosl.org
Subject: Rich man's version of AIO on Linux 2.6.x?
Date: Fri, 22 May 2009 02:59:53 +0200	[thread overview]
Message-ID: <c384c5ea0905211759v11408a03o570980a34d02f0ff@mail.gmail.com> (raw)

Hello,

On the state-of-art of asynchronous I/O in Linux. I understand we have
full support for AIO in the Linux 2.6.x kernel but I cannot find how
to use it from user space.


I would like to exploit AIO in hardware and the device driver for it,
by keeping the hardware performing I/O at all times (no setup latency
between requests by allowing multiple
I/O requests to be queued in hardware). Note this is a character
device, not a filesystem.

I implemented aio_read() and aio_write() on my character device
interface, but it's never been called; read() and write() is called
instead.

>From "Understanding the Linux kernel, 3rd edition" I read that glibc
indeed implements aio_read() and friends itself, not through the
kernel AIO syscalls.

<Quote>
Essentially, the aio_read( ) or aio_write( ) library function clones
the current process and lets the child invoke the synchronous read( )
or write( ) system calls; However, this "poor man's" version of the
POSIX functions is significantly slower than a version that uses a
kernel-level implementation of asynchronous I/O.
<End Quote>

I am looking for a rich man's way to use the kernel functionality;
essentially I want my drivers aio_read and aio_write ops to be called.

Regards,
-- 
Leon

             reply	other threads:[~2009-05-22  0:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-22  0:59 Leon Woestenberg [this message]
2009-05-22 14:54 ` Michal Hocko
2009-05-23 12:45   ` Leon Woestenberg

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