New != Faster
kris at obsecurity.org
Mon Jun 4 23:27:38 UTC 2007
On Mon, Jun 04, 2007 at 06:07:31PM -0500, Tim Daneliuk wrote:
> Kris Kennaway wrote:
> >On Mon, Jun 04, 2007 at 08:54:50PM +0100, Chris wrote:
> >>On 04/06/07, Colin Percival <cperciva at freebsd.org> wrote:
> >>both of these have been confirmed numerous times by different people
> >>so sweeping them under the carpet and saying they simply not true
> >>would be wrong.
> >My detailed measurements of disk performance and those of others I am
> >aware of contradicts your claim: 6.x equals or outperforms 4.x on disk
> >I/O (depends on driver) and filesystem I/O. The only true part of it
> >is the "under QUOTA" part, which as you know from past discussions, is
> >still under Giant in 6.x. As you also know, there is a patch to
> >address this which is awaiting user testing. Have you tested it yet?
> Kris -
> It's been awhile since I tracked -current, so forgive me if this is
> a stupid question but ... Is it the case that the 6.x drivers are
> all now SMP-safe or do some still live under GIANT?
There are still some storage drivers in 6.x that are giant-locked.
Note that in most cases this doesn't really matter, since typically
there is very little else on the system that uses Giant, so there is
little contention with other systems and performance is good. One
situation where it would hurt on 6.x is if you have quotas enabled.
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