Re: SCSI Disk layer performance

[Patrick Mansfield <patmans@us.ibm.com>]

On Thu, Jan 29, 2004 at 01:26:50PM +0100, George Magklaras wrote:

> The 2.4.21-9EL might have clever things backported into it, but it is 
> still missing essential things that can make a difference in the block 
> layer, like an anticipatory I/O schedule. My impression is that all 
> 2.4 kernels use the Linus Elevator. That works well with moderate SMP 
> loads, but it does not perform well on my large-ish Hardware RAID0 
> 1.1Tbyte ext3 partition on a Power Vault 220S with a Dell PERC4 host 
> adapter. The 2.6.1 does work a lot more better in that sense, giving 
> me an average read of 90 Mbytes/sec as opposed to 
> 60+somethingMbytes/sec I used to get before with 2.4.21-9ELsmp.
> 
> The new I/O schedulers (let alone driver maturity issues) are the way 
> to go for maximum performance! I won't place -for the moment- a 2.6 on 
> a production grade system, but in a couple of releases, I will put 2.4 
> in the museum :-) with respect to SCSI I/O performance.

How does the anticipatory scheduler compare to the deadline scheduler on
your system?

What types of IO are you doing?

-- Patrick Mansfield