On Fri 22-05-09 02:59:53, Leon Woestenberg wrote: > Hello, Hi > > 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. Check the libaio library (io_submit and friends) > > Regards, > -- > Leon > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Michal Hocko L3 team SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic
