Messages in this thread | | | Date | Thu, 31 Jul 2003 14:15:17 -0700 | From | Andrew Morton <> | Subject | Re: Disk performance degradation |
| |
mru@users.sourceforge.net (Måns Rullgård) wrote: > > Mike Dresser <mdresser_l@windsormachine.com> writes: > > > Probably for reasons like that. For some reason, I can't set my ICH4 > > based controller(ASUS P4B533) and Quantum Fireball AS40.0 to more than > > 255. Kernel is 2.4.21 > > It appears that in 2.[56] kernels the unit for readahead is bytes, > rather than sectors, as used in 2.4 kernels.
The ioctl which is used by
blockdev --setra
is still in 512-byte units.
There are other backdoors such as IDE-private /proc files which can be used to set readahead. I'm not sure what units they use, and I don't know what mechanism hdparm is using to diddle readahead.
Whatever it is, I suggest you ignore it and use /sbin/blockdev; it works for all disk types.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |