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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 2/2] powerpc/mm: don't do tlbie for updatepp request with
 NO HPTE fault
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Date: Tue, 02 Dec 2014 12:21:24 +0530
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Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:

> On Mon, 2014-11-03 at 20:21 +0530, Aneesh Kumar K.V wrote:
>> --- a/arch/powerpc/mm/hash_native_64.c
>> +++ b/arch/powerpc/mm/hash_native_64.c
>> @@ -283,11 +283,11 @@ static long native_hpte_remove(unsigned long hpte_group)
>>  
>>  static long native_hpte_updatepp(unsigned long slot, unsigned long newpp,
>>                                  unsigned long vpn, int bpsize,
>> -                                int apsize, int ssize, int local)
>> +                                int apsize, int ssize, unsigned long flags)
>>  {
>>         struct hash_pte *hptep = htab_address + slot;
>>         unsigned long hpte_v, want_v;
>> -       int ret = 0;
>> +       int ret = 0, local = 0;
>>  
>>         want_v = hpte_encode_avpn(vpn, bpsize, ssize);
>>  
>> @@ -322,8 +322,15 @@ static long native_hpte_updatepp(unsigned long slot, unsigned long newpp,
>>                 }
>>                 native_unlock_hpte(hptep);
>>         }
>> -       /* Ensure it is out of the tlb too. */
>> -       tlbie(vpn, bpsize, apsize, ssize, local);
>> +
>> +       if (flags & HPTE_LOCAL_UPDATE)
>> +               local = 1;
>> +       /*
>> +        * Ensure it is out of the tlb too if it is not a nohpte fault
>> +        */
>> +       if (!(flags & HPTE_NOHPTE_UPDATE))
>> +               tlbie(vpn, bpsize, apsize, ssize, local);
>> +
>>         return ret;
>>  }
>
> An additional refinement we discussed that I'd like you to test/measure
> is to basically always be local for updatepp unless we have a flag that
> forces us not to.
>
> That flag would be set by copro faults only.
>
> Can you do something on top of this series ?

Yes. Will try that out.

-aneesh