Date: Thu, 12 Aug 2010 14:25:40 +0200 From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no> To: Garrett Cooper <gcooper@FreeBSD.org> Cc: freebsd-hackers@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: Why is TUNABLE_INT discouraged? Message-ID: <8662zg586z.fsf@ds4.des.no> In-Reply-To: <AANLkTimbkTQiNgYCYFnTXMpRe9koJGrq1%2BYoq5-fVmFD@mail.gmail.com> (Garrett Cooper's message of "Thu, 12 Aug 2010 01:08:48 -0700") References: <AANLkTinKaiGFhKRgqQ%2BFjm=02VfWCxULe0a68y-PkJx6@mail.gmail.com> <86fwyq8rsc.fsf@ds4.des.no> <i3kbis$73l$1@dough.gmane.org> <86d3tujh72.fsf@ds4.des.no> <AANLkTi=puD%2B-WeZ%2BFGdtZtw1v%2BNnGD_htwNa%2BEn9fcML@mail.gmail.com> <864of680wv.fsf@ds4.des.no> <AANLkTinraF50O%2Bcp_h1m6TODnoz_7R3WXfjTanh-86mn@mail.gmail.com> <AANLkTikU6fLzWL-n6fCtvaTsXWGis7ydKM1qJaV=WRJ%2B@mail.gmail.com> <8662zkurx9.fsf@ds4.des.no> <AANLkTimbkTQiNgYCYFnTXMpRe9koJGrq1%2BYoq5-fVmFD@mail.gmail.com>
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Garrett Cooper <gcooper@FreeBSD.org> writes:
> Dag-Erling Sm=C3=B8rgrav <des@des.no> writes:
> > It might be a good idea to introduce TUNABLE_POINTER and TUNABLE_SIZE.
> I would actually argue against doing that because it would only create
> divergence between sysctl and tunable KPIs...
Not if we also introduce corresponding SYSCTLs. Note that my idea is to
have these as aliases for the correct primitive types.
> (BTW, when you say TUNABLE_SIZE, I assume it would be a size_t quantity?)
Yes.
> Something might need to be done to the values returned by the tunables
> though, because they don't respect boundaries, and can overflow right
> now (which exacerbates the issue with values crammed into smaller
> datatypes)...
Yes. How about this:
- rename getenv_quad() to getenv_signed() and getenv_unsigned()
- add min / max arguments
- implement getenv_quad() (and all the others) in terms of
getenv_number()
e.g.=20
int
getenv_uint(const char *name, unsigned int *data)
{
unsigned long long tmp;
int rval;
if ((rval =3D getenv_unsigned(name, &tmp, 0, UINT_MAX)) =3D=3D 0)
*data =3D (unsigned int)tmp;
return (rval);
}
(note that due to the min / max arguments, the complexity of handling
both signed and unsigned values in the same function probably exceeds
the complexity of having two very similar functions)
DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no
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