On Thu, Oct 14, 2004 at 01:10:01PM -0700, Yasushi Saito wrote:It is a huge performance win, at least on the 2.4-based RHEL kernel. Large reads (~256K) using 4K iocbs are very slow on a large RAID, while after I coded a similar patch I got a substantial speedup.
This is a patch against 2.6.9-rc3-mm3 that add supports for vectored async I/O. It adds two additional commands, IO_CMD_PREADV and IO_CMD_PWRITEV to libaio.h. The below is roughly what I did:
How does this differ substantially from lio_listio() of each I/O
range? Does it have some significant performance win, or is it just
aiming for a completeness that POSIX doesn't (to my knowledge) specify?