Date: Wed, 29 Mar 2006 20:52:36 +0100 From: Chris <chrcoluk@gmail.com> To: "Robert Watson" <rwatson@freebsd.org> Cc: =?ISO-8859-1?Q?Dag-Erling_Sm=F8rgrav?= <des@des.no>, "Conrad J. Sabatier" <conrads@cox.net>, freebsd-stable@freebsd.org, bmilekic@freebsd.org Subject: Re: nmbclusters Message-ID: <3aaaa3a0603291152g2ea1fcbdo57342e3031882060@mail.gmail.com> In-Reply-To: <20060329175256.W19236@fledge.watson.org> References: <3aaaa3a0603281134sd0d4e16x@mail.gmail.com> <20060329030459.40be9cb2.conrads@cox.net> <861wwlcsnj.fsf@xps.des.no> <20060329175256.W19236@fledge.watson.org>
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On 29/03/06, Robert Watson <rwatson@freebsd.org> wrote: > > On Wed, 29 Mar 2006, Dag-Erling Sm=F8rgrav wrote: > > > "Conrad J. Sabatier" <conrads@cox.net> writes: > >> Chris <chrcoluk@gmail.com> wrote: > >>> so [kern.ipc.nmbclusters] has no affect, has this become a read only > >>> tunable again only settable in loader.conf? > >> To the best of my knowledge, this has *always* been a loader tunable, > >> not configurable on-the-fly. > > > > kern.ipc.nmbclusters is normally computed at boot time. A compile- tim= e > > option to override it was introduced in 2.0-CURRENT. At that time, it = was > > defined in param.c. A read-only sysctl was introduced in 3.0-CURRENT. = It > > moved from param.c to uipc_mbuf.c in 4.0-CURRENT, then to subr_mbuf.c w= hen > > mballoc was introduced in 5.0-CURRENT; became a tunable at some point a= fter > > that; then moved again to kern_mbuf.c when mballoc was replaced with mb= uma > > in 6.0-CURRENT. That is the point where it became read-write, for no g= ood > > reason that I can see; setting it at runtime has no effect, because the= size > > of the mbuf zone is determined at boot time. Perhaps Bosko (who wrote = both > > mballoc and mbuma, IIRC) knows. > > Paul Saab from Yahoo! has a set of patches that allow run-time nmbcluster= s > changes to be implemented -- while it won't cause the freeing of clusters > referenced, it goes through and recalculates dependent variables, propaga= tes > them into UMA, etc. I believe they're running with this patch on 6.x, an= d I > expect that they will be merged to -CURRENT and -STABLE in the relatively= near > future. Not before 6.1, however. > > If the nmbclusters setting really has no effect right now, we should mark= the > sysctl as read-only to make it more clear it doesn't, since allowing it t= o be > set without taking effect is counter-intuitive. > > Robert N M Watson > thanks for everyones responses. My 5.4 servers seem to accept the tunable been changed at runtime although this could be a bug and it isnt really changing? 4.x I know was a boot only tunable. I have tested this now in loader.conf and it works so it seems its a minor bug where the error message is replaced by a false success output. Chris
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