Subject: Is O_DIRECT useless on NetBSD?
To: None <tech-kern@NetBSD.org>
From: Roland Illig <firstname.lastname@example.org>
Date: 11/21/2007 12:47:01
I have written a little archiver program, since both pax and tar cannot
create files larger than 4 GB. :(
Since I expect the program to not read any data twice, I added the
O_DIRECT flag to all open(2) calls. But top(1) still tells me that most
of my RAM is occupied by "FILE", and only about 1 megabyte is "Free".
All the involved filesystems are ffs. So did I understand O_DIRECT
wrong? Or is it at all impossible to disable the kernel cache for file data?