linux-kernel - Re: [PATCH v3 2/2] powerpc/mm/hugetlb: Add support for 1G huge pages

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Date:   Thu, 18 May 2017 18:47:01 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        akpm@...ux-foundation.org,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 2/2] powerpc/mm/hugetlb: Add support for 1G huge pages

"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> writes:

> On Thursday 18 May 2017 10:51 AM, Michael Ellerman wrote:
>> "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> writes:
>> 
>>> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch
>>> enables the usage of 1G page size for hugetlbfs. This also update the helper
>>> such we can do 1G page allocation at runtime.
>>>
>>> We still don't enable 1G page size on DD1 version. This is to avoid doing
>>> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add
>>> radix__tlb_flush_pte_p9_dd1()
>>>
>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
>>> ---
>>>   arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++
>>>   arch/powerpc/mm/hugetlbpage.c                |  7 +++++--
>>>   arch/powerpc/platforms/Kconfig.cputype       |  1 +
>>>   3 files changed, 16 insertions(+), 2 deletions(-)
>> 
>> I think this patch is OK, but it's very confusing because it doesn't
>> mention that it's only talking about *generic* gigantic page support.
>
> What you mean by generic gigantic page ? what is supported here is the 
> gigantic page with size 1G alone ?

What about 16G pages on pseries.

And all the other gigantic page sizes that Book3E supports?

cheers