A: http://en.wikipedia.org/wiki/Top_post Q: Where do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? A: No. Q: Should I leave quotations after my reply? On Fri, Dec 22, 2006 at 10:04:16AM +0800, colin wrote: > > Hi Erik, > My colleague said that when use direct I/O on USB disk that has a ext3 > partition, open can succeed, but read fails. Then you're reading the wrong way. > I know that filesystem must have some system calls for direct I/O, and open > with O_DIRECT flag will check if these system calls exist. > But why does read fail? Is it that direst I/O cannot use on USB disk? Because you probably don't read() the right way. For direct IO to succeed, you need: - a device or filesystem that supports it - a page aligned buffer - transfers need to be multiples of the sector size in 2.6 or multiples of the soft block size in 2.4 Erik -- They're all fools. Don't worry. Darwin may be slow, but he'll eventually get them. -- Matthew Lammers in alt.sysadmin.recovery -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
