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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: "Michal Suchánek" <msuchanek@suse.de>, linuxppc-dev@lists.ozlabs.org
Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au
Subject: Re: [PATCH V3 08/10] powerpc/mm/hash: Increase VA range to 128TB
Date: Mon, 06 Mar 2017 08:09:52 +0530	[thread overview]
Message-ID: <8760jndt6v.fsf@skywalker.in.ibm.com> (raw)
In-Reply-To: <20170303170013.3f5bfd12@kitsune.suse.cz>

Michal Such=C3=A1nek <msuchanek@suse.de> writes:

> Hello,
>
> On Sun, 19 Feb 2017 15:37:15 +0530
> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:
>
>> We update the hash linux page table layout such that we can support
>> 512TB. But we limit the TASK_SIZE to 128TB. We can switch to 128TB by
>> default without conditional because that is the max virtual address
>> supported by other architectures. We will later add a mechanism to
>> on-demand increase the application's effective address range to 512TB.
>>=20
>> Having the page table layout changed to accommodate 512TB  makes
>> testing large memory configuration easier with less code changes to
>> kernel
>>=20
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

....

> index b64daf124fee..c7ca70dc3ba5 100644
>> --- a/arch/powerpc/kernel/paca.c
>> +++ b/arch/powerpc/kernel/paca.c
>> @@ -253,8 +253,15 @@ void copy_mm_to_paca(struct mm_struct *mm)
>>  	get_paca()->mm_ctx_id =3D context->id;
>>  #ifdef CONFIG_PPC_MM_SLICES
>>  	get_paca()->mm_ctx_low_slices_psize =3D
>> context->low_slices_psize;
>> +	/*
>> +	 * We support upto 128TB for now. Hence copy only 128/2
>> bytes.
>> +	 * Later when we support tasks with different max effective
>> +	 * address, we can optimize this based on mm->task_size.
>> +	 */
>> +	BUILD_BUG_ON(TASK_SIZE_USER64 !=3D TASK_SIZE_128TB);
>
> Can this be handled by KConfig?
> Above I see=20

I am reworking the series so that we depend on mm->task_size. Will send
a new version soon.



>> +#ifdef CONFIG_PPC_BOOK3S_64
>> +#define TASK_SIZE_USER64 TASK_SIZE_128TB
>> +#else
>> +#define TASK_SIZE_USER64 TASK_SIZE_64TB
>> +#endif
> and=20
>> #ifdef CONFIG_PPC_MM_SLICES
>> ILD_BUG_ON(TASK_SIZE_USER64 !=3D TASK_SIZE_128TB)
>
> which boils down to
> #ifndef CONFIG_PPC_BOOK3S_64
> #ifdef CONFIG_PPC_MM_SLICES
> #error TASK_SIZE_USER64 !=3D TASK_SIZE_128TB
>
>
>>  	memcpy(&get_paca()->mm_ctx_high_slices_psize,
>> -	       &context->high_slices_psize, SLICE_ARRAY_SIZE);
>> +	       &context->high_slices_psize, TASK_SIZE_128TB >> 41);
>
> Can we avoid magic numbers, please?
>

Since array is 4 bytes per each TB which is documented else where.
Considering we are just converting max range there, do we need that as a
macro ?

-aneesh

  reply	other threads:[~2017-03-06  2:41 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-19 10:07 [PATCH V3 00/10] powerpc/mm/ppc64: Add 128TB support Aneesh Kumar K.V
2017-02-19 10:07 ` [PATCH V3 01/10] powerpc/mm/slice: Convert slice_mask high slice to a bitmap Aneesh Kumar K.V
2017-02-21  4:43   ` Balbir Singh
2017-02-21  6:56     ` Aneesh Kumar K.V
2017-02-22  0:16       ` Balbir Singh
2017-02-19 10:07 ` [PATCH V3 02/10] powerpc/mm/slice: Update the function prototype Aneesh Kumar K.V
2017-02-21  4:44   ` Balbir Singh
2017-02-19 10:07 ` [PATCH V3 03/10] powerpc/mm/hash: Move kernel context to the starting of context range Aneesh Kumar K.V
2017-02-21  4:51   ` Balbir Singh
2017-02-19 10:07 ` [PATCH V3 04/10] powerpc/mm/hash: Support 68 bit VA Aneesh Kumar K.V
2017-02-22  0:15   ` Balbir Singh
2017-02-19 10:07 ` [PATCH V3 05/10] powerpc/mm: Move copy_mm_to_paca to paca.c Aneesh Kumar K.V
2017-02-19 10:07 ` [PATCH V3 06/10] powerpc/mm: Remove redundant TASK_SIZE_USER64 checks Aneesh Kumar K.V
2017-02-22  0:17   ` Balbir Singh
2017-02-19 10:07 ` [PATCH V3 07/10] powerpc/mm/slice: Use mm task_size as max value of slice index Aneesh Kumar K.V
2017-02-19 10:07 ` [PATCH V3 08/10] powerpc/mm/hash: Increase VA range to 128TB Aneesh Kumar K.V
2017-03-03 16:00   ` Michal Suchánek
2017-03-06  2:39     ` Aneesh Kumar K.V [this message]
2017-03-06  3:37       ` Aneesh Kumar K.V
2017-03-06 15:20         ` Michal Suchánek
2017-02-19 10:07 ` [PATCH V3 09/10] powerpc/mm/slice: Move slice_mask struct definition to slice.c Aneesh Kumar K.V
2017-03-03 15:44   ` Michal Suchánek
2017-02-19 10:07 ` [PATCH V3 10/10] powerpc/mm/slice: Update slice mask printing to use bitmap printing Aneesh Kumar K.V
2017-02-22  0:20   ` Balbir Singh

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