Date: Thu, 18 Jan 2007 22:04:10 +0800 From: LI Xin <delphij@delphij.net> To: Randall Stewart <rrs@cisco.com> Cc: freebsd-net <freebsd-net@FreeBSD.org>, Christian Brueffer <brueffer@FreeBSD.org> Subject: Re: mbuf large clusters Message-ID: <45AF7E5A.4080109@delphij.net> In-Reply-To: <45AF7CF8.6030102@cisco.com> References: <45AF55DE.1070700@cisco.com> <45AF7962.7040407@cisco.com> <20070118135319.GB1874@haakonia.hitnet.RWTH-Aachen.DE> <45AF7CF8.6030102@cisco.com>
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Randall Stewart wrote:
> Christian Brueffer wrote:
>=20
>>
>> Not sure if I'm understanding you correctly, but kern.ipc.nmbclusters =
is
>> a tunable not a sysctl, so it has to be set in /boot/loader.conf or at=
>> the loader prompt (see loader(8)).
>>
>=20
> Not in current from what I see (if
> I understand this correctly of course):
> -----------------------------------------------------
> static int
> sysctl_nmbclusters(SYSCTL_HANDLER_ARGS)
> {
> int error, newnmbclusters;
>=20
> newnmbclusters =3D nmbclusters;
> error =3D sysctl_handle_int(oidp, &newnmbclusters, sizeof(int), req=
);
> if (error =3D=3D 0 && req->newptr) {
> if (newnmbclusters > nmbclusters) {
> nmbclusters =3D newnmbclusters;
> uma_zone_set_max(zone_clust, nmbclusters);
> EVENTHANDLER_INVOKE(nmbclusters_change);
> } else
> error =3D EINVAL;
> }
> return (error);
> }
> SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbclusters, CTLTYPE_INT|CTLFLAG_RW,
> &nmbclusters, 0, sysctl_nmbclusters, "IU",
> "Maximum number of mbuf clusters allowed");
>=20
> -----------------------------------------------------
>=20
> It looks to me like it lets you INCREASE the value from
> the calculated system value.. but NOT shrink it :-0
No, shrinking it is not currently supported... It can easily trigger
'zonelimit' livelock if not handled properly. On the other hand, the
code seems to have some problem as it allows setting an upper limit when
there is no upper limit (nmbclusters=3D0).
Cheers,
--=20
Xin LI <delphij@delphij.net> http://www.delphij.net/
FreeBSD - The Power to Serve!
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