Re: Linux 2.6.29

[Andrew Morton]

On Wed, 25 Mar 2009 16:23:08 -0700 (PDT) Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> 
> 
> On Wed, 25 Mar 2009, Theodore Tso wrote:
> > > 
> > > The problem being that unlike the ratio, there's no sane default value 
> > > that you can at least argue is not _entirely_ pointless.
> > 
> > Well, if the maximum time that someone wants to wait for an fsync() to
> > return is one second, and the RAID array can write 100MB/sec
> 
> How are you going to tell the kernel that the RAID array can write 
> 100MB/s?
> 
> The kernel has no idea.
> 

userspace can do it quite easily.  Run a self-tuning script after
installation and when the disk hardware changes significantly.

It is very disappointing that nobody appears to have attempted to do
_any_ sensible tuning of these controls in all this time - we just keep
thrashing around trying to pick better magic numbers in the base kernel. 

Maybe we should set the tunables to 99.9% to make it suck enough to
motivate someone.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/