zfs arc - just take it all and be good to me

[Marco van Tol]

On Wed, Aug 25, 2010 at 06:05:27AM +1000, Peter Jeremy wrote:
> On 2010-Aug-24 17:00:36 +0200, Ollivier Robert <roberto at keltia.freenix.fr> wrote:
> >According to Peter Jeremy:
> >> I suspect Artem is referring to his patch at http://pastebin.com/ZCkzkWcs
> >> which I have tweaked somewhat (see the last patch in 
> >> http://www.freebsd.org/cgi/query-pr.cgi?pr=146410 ).
> >
> >Thanks, cou you please send it in a non-QP-encoded form please?
> 
> See attached.
> 
> >> Whilst these patches _are_ hacks, they seem to do a good job of
> >> making ZFS and UFS play together.
> >
> >Is the patch only useful in these mixed situations or could it be also interestng for those of use running full-zfs (cf. http://www.keltia.net/howtos/zfsboot)?
> 
> I think it will be useful.  As well as the trivial fix to count
> "cache" as "free" space (which is now in -stable), the intent of the
> patch is to improve the ability of ZFS to apply pressure to the VM
> subsystem.  In theory, this should improve overall system performance
> even in a ZFS-only environment where there is memory pressure due to
> large, long-running processes

Would the inactive pages of the long running processes be swapped out in
favour of the arc?  That would be great I think as long as that is made
clear at an obvious place so people don't get worried about swap usage
on a system that "shouldn't need to swap out anything".

/usr/src/UPDATING springs to mind, together with quick hints on how to
see that the swapped out pages are harmless. :)

Marco van Tol

P.S. Forgive me if what I say is bs, within what I know it makes sense.
:)

-- 
A male gynecologist is like an auto mechanic who never owned a car.
- Carrie Snow
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