svn commit: r208165 - in head/sys: kern mips/conf mips/include mips/mips mips/rmi mips/rmi/dev/xlr

[Jayachandran C.]

On Mon, Aug 9, 2010 at 5:31 AM, Attilio Rao <attilio at freebsd.org> wrote:
> 2010/5/16 Randall Stewart <rrs at freebsd.org>:
>> Author: rrs
>> Date: Sun May 16 19:43:48 2010
>> New Revision: 208165
>> URL: http://svn.freebsd.org/changeset/base/208165
>>
>> Log:
>>  This pushes all of JC's patches that I have in place. I
>>  am now able to run 32 cores ok.. but I still will hang
>>  on buildworld with a NFS problem. I suspect I am missing
>>  a patch for the netlogic rge driver.
>>
>>  JC check and see if I am missing anything except your
>>  core-mask changes
>
>
>> Modified: head/sys/kern/subr_smp.c
>> ==============================================================================
>> --- head/sys/kern/subr_smp.c    Sun May 16 19:25:56 2010        (r208164)
>> +++ head/sys/kern/subr_smp.c    Sun May 16 19:43:48 2010        (r208165)
>> @@ -503,7 +503,10 @@ smp_topo_none(void)
>>        top = &group[0];
>>        top->cg_parent = NULL;
>>        top->cg_child = NULL;
>> -       top->cg_mask = (1 << mp_ncpus) - 1;
>> +       if (mp_ncpus == sizeof(top->cg_mask) * 8)
>> +               top->cg_mask = -1;
>> +       else
>> +               top->cg_mask = (1 << mp_ncpus) - 1;
>>        top->cg_count = mp_ncpus;
>>        top->cg_children = 0;
>>        top->cg_level = CG_SHARE_NONE;
>>
>
> ... and this is why I particulary hate big commits with complete lack
> of technical details.
>
> This particulary chunk was supposed to fix a nasty and completely MI
> bug that some users have already met (kern/148698). The complete lack
> of details didn't help in identify the issue neither that it was a
> valuable fix.
>
> The fix is, however, improper (there is no clear relationship between
> the multiplication and why that happens) thus I would rather use what
> Joe has reported in the PR.


I was not aware of the PR when I sent this changes to rrs@, and this
went as a part of MIPS SMP support for XLR which has 32 CPUs

But I'm not sure that the current change is correct, cg_mask is of
type cpumask_t and I don't think it is guaranteed to be 32 bit (as it
is a machine dependent type).

JC.