RELENG_4 -> 5 -> 6: significant performance regression

[Kris Kennaway]

On Thu, Apr 27, 2006 at 08:26:06PM +0200, ml at sd2i.com wrote:
> Kris Kennaway a ?crit :
> >On Thu, Apr 27, 2006 at 05:08:11PM +0300, Dmitry Pryanishnikov wrote:
> >
> >
> >>options 	QUOTA
> >
> >This definitely effects performance on 6.x since it makes your
> >filesystem giant-locked, which may also interfere with your network
> >processing.
> 
> Why would QUOTA affect performance more on 6.x than 4.x ? I would like 
> to understand because i think a system cannot be secure without QUOTA

It makes filesystem writes acquire Giant, which blocks other kernel
code that needs to also acquire Giant.  When the need to acquire Giant
was removed from the mainstream UFS code in 6.0 it was an enormous
performance improvement.

Kris
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