Re: disk performance still wrecked in 2.4!

[Andre Hedrick]

there is an ata patch that allows for setting the elevator to "noop"
at compile time only, plus a few other fixes.

On 30 Jun 2000, Michal Ostrowski wrote:

> 
> I mentioned a similar problem about a month ago.  Jens Axboe provided
> a patch which re-worked the elevator code and restored performance to
> 2.2 levels.  I think you'll be able to find his patches in the
> "people" directory.
> 
> Michal Ostrowski
> [e-mail]
> 
> 
> [e-mail] ("Daniel Summer") writes:
> 
> > Hello kernel hackers. I have been concerned about a serious performance 
> > issue affecting bonnie disk benchmark results that has persisted throughout 
> > 2.3 and 2.4 development. This issue has been brought up many times on this 
> > list and there doesn't seem to be a consensus as to what the origin of the 
> > problem is. Some have pointed to the elevator code, some to the VM 
> > subsystem, some to the block interfaces.
> > 
> > Joel Jacobsen of 3ware pointed out that these poor benchmark results may 
> > arise from problems with the buffer cache (see his comments below). I went 
> > ahead and ran some benchmarks with different quantities of RAM across 2.2 
> > and 2.4 to see if I could shed some light on this.
> > 
> > I found that bumping the RAM from 512megs to a gig gives a huge performance 
> > boost under 2.4 and makes little to no impact under 2.2.16. Even with a gig 
> > of RAM though, 2.4 still performs much worse than 2.2 at sequential reads.
> > 
> > So what does this mean? does anyone else agree that the buffer cache may be 
> > where this problem is coming from?
> > 
> 
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Andre Hedrick
The Linux ATA/IDE guy