Date: Mon, 27 Sep 2010 16:32:34 -0700 From: Joshua Neal <jdneal@gmail.com> To: Robert Watson <rwatson@freebsd.org> Cc: "sbruno@freebsd.org" <sbruno@freebsd.org>, freebsd-current@freebsd.org, Sean Bruno <seanbru@yahoo-inc.com>, "current@freebsd.org" <current@freebsd.org> Subject: Re: MAXCPU preparations Message-ID: <AANLkTik0Eq2w565cgszvXK4kgDo08%2B28iPkk3CsU-LqC@mail.gmail.com> In-Reply-To: <alpine.BSF.2.00.1009272240340.69239@fledge.watson.org> References: <1285601161.7245.7.camel@home-yahoo> <1285604516.7245.16.camel@home-yahoo> <alpine.BSF.2.00.1009272210040.69239@fledge.watson.org> <201009271738.19497.jhb@freebsd.org> <alpine.BSF.2.00.1009272240340.69239@fledge.watson.org>
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I hit this bug at one point, and had to bump MEMSTAT_MAXCPU. It's
already asking the kernel for the max number and throwing an error if
it doesn't agree:
if (sysctlbyname("kern.smp.maxcpus", &maxcpus, &size, NULL, 0) < 0) =
{
[...]
if (maxcpus > MEMSTAT_MAXCPU) {
list->mtl_error =3D MEMSTAT_ERROR_TOOMANYCPUS;
return (-1);
}
I was thinking a more future-proof fix would be to get rid of the
static allocations and allocate the library's internal structures
based on the value of kern.smp.maxcpus.
- Joshua
On Mon, Sep 27, 2010 at 2:42 PM, Robert Watson <rwatson@freebsd.org> wrote:
>
> On Mon, 27 Sep 2010, John Baldwin wrote:
>
>> Also, I think we should either fix MAXCPU to export the SMP value to
>> userland, or hide it from userland completely. =A0Exporting the UP value=
is
>> Just Wrong (tm).
>
> Well, it's useful in the sense that it tells you what the maximum number =
of
> CPUs a kernel can support is, which is helpful, especially if you're futz=
ing
> with MAXCPU as a kernel option :-).
>
> But, more generally, many things that use MAXCPU should probably use eith=
er
> mp_maxid or DPCPU. =A0Not everything, but most things.
>
> Robert
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