svn commit: r210846 - in head/sys/mips: include mips

[Jayachandran C.]

On Fri, Aug 6, 2010 at 11:11 AM, Alan Cox <alc at cs.rice.edu> wrote:
> On 08/05/2010 09:25, Jayachandran C. wrote:
>>
>> On Thu, Aug 5, 2010 at 4:26 PM, Jayachandran C.
>> <c.jayachandran at gmail.com>  wrote:
>>
>>>
>>> On Thu, Aug 5, 2010 at 11:43 AM, Alan Cox<alc at cs.rice.edu>  wrote:
>>>
>>>>
>>>> Just an observation ...
>>>>
>>>> Jayachandran C. wrote:
>>>>
>>>>>
>>>>> Author: jchandra
>>>>> Date: Wed Aug  4 14:12:09 2010
>>>>> New Revision: 210846
>>>>> URL: http://svn.freebsd.org/changeset/base/210846
>>>>>
>>>>> Log:
>>>>>  Add 3 level page tables for MIPS in n64.
>>>>>    - 32 bit compilation will still use old 2 level page tables
>>>>>  - re-arrange pmap code so that adding another level is easier
>>>>>  - pmap code for 3 level page tables for n64
>>>>>  - update TLB handler to traverse 3 levels in n64
>>>>>    Reviewed by:        jmallett
>>>>>
>>>>
>>>> MIPS doesn't really need to use atomic_cmpset_int() in situations like
>>>> this
>>>> because the software dirty bit emulation in trap.c acquires the pmap
>>>> lock.
>>>>  Atomics like this appear to be a carryover from i386 where the
>>>> hardware-managed TLB might concurrently set the modified bit.
>>>>
>>>
>>> Then I guess we should be able to use *pte directly, without pbits,
>>> obits and the retry loop.
>>> Will try this change...
>>>
>>
>> Can you have a look at the attached patch and see if it is okay?  This
>> has the above changes, and I have attempted to fix the other issue you
>> had reported on wired mapping count too.
>>
>
> The patch looks good.
>
>> There are a few calls for loadandclear() on pte too, with pmap lock
>> held, can this be avoided too?
>>
>
> I haven't looked at them, but almost certainly yes.

The calls are in pmap_remove_pte(), pmap_remove_all() and
get_pv_entry(). the attached patch changes it normal pointer
operations. Thought I would post it for review before checking in...

Thanks,
JC.
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