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From: Christophe LEROY <christophe.leroy@c-s.fr>
To: Scott Wood <oss@buserror.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [v3,2/3] powerpc: get hugetlbpage handling more generic
Date: Fri, 25 Nov 2016 09:14:03 +0100	[thread overview]
Message-ID: <aa9a2f8a-a480-0cc9-adf6-4017c771fb46@c-s.fr> (raw)
In-Reply-To: <20161124052330.GA17212@home.buserror.net>



Le 24/11/2016 à 06:23, Scott Wood a écrit :
> On Wed, Sep 21, 2016 at 10:11:54AM +0200, Christophe Leroy wrote:
>> Today there are two implementations of hugetlbpages which are managed
>> by exclusive #ifdefs:
>> * FSL_BOOKE: several directory entries points to the same single hugepage
>> * BOOK3S: one upper level directory entry points to a table of hugepages
>>
>> In preparation of implementation of hugepage support on the 8xx, we
>> need a mix of the two above solutions, because the 8xx needs both cases
>> depending on the size of pages:
>> * In 4k page size mode, each PGD entry covers a 4M bytes area. It means
>> that 2 PGD entries will be necessary to cover an 8M hugepage while a
>> single PGD entry will cover 8x 512k hugepages.
>> * In 16 page size mode, each PGD entry covers a 64M bytes area. It means
>> that 8x 8M hugepages will be covered by one PGD entry and 64x 512k
>> hugepages will be covers by one PGD entry.
>>
>> This patch:
>> * removes #ifdefs in favor of if/else based on the range sizes
>> * merges the two huge_pte_alloc() functions as they are pretty similar
>> * merges the two hugetlbpage_init() functions as they are pretty similar
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>
> With this patch on e6500, running the hugetlb testsuite results in the
> system hanging in a storm of OOM killer invocations (I'll try to debug
> more deeply later).  This patch also changes the default hugepage size on
> FSL book3e from 4M to 16M.
>

Regarding the default hugepage size, it is a result of the merge of the 
two hugetlbpage_init().
Should I add an ifdef to get 4M on FSL book3e by default ?
What's the reason for selecting different hugepage sizes depending on 
the CPU ? I thought default size was selected based on what was existing.

What testsuite do you run exactly ?

Christophe

  reply	other threads:[~2016-11-25  8:15 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-21  8:11 [PATCH v3 0/3] powerpc: implementation of huge pages for 8xx Christophe Leroy
2016-09-21  8:11 ` [PATCH v3 1/3] powerpc: port 64 bits pgtable_cache to 32 bits Christophe Leroy
2016-09-22  7:27   ` Aneesh Kumar K.V
2016-09-21  8:11 ` [PATCH v3 2/3] powerpc: get hugetlbpage handling more generic Christophe Leroy
2016-09-21 16:58   ` Aneesh Kumar K.V
2016-11-24  5:23   ` [v3,2/3] " Scott Wood
2016-11-25  8:14     ` Christophe LEROY [this message]
2016-12-05  2:58       ` Scott Wood
2016-12-06  1:18   ` [PATCH v3 2/3] " Scott Wood
2016-12-06  6:34     ` Christophe LEROY
2016-12-07  1:06       ` Scott Wood
2016-12-07  6:59         ` Christophe LEROY
2016-09-21  8:11 ` [PATCH v3 3/3] powerpc/8xx: Implement support of hugepages Christophe Leroy
2016-09-21 16:58   ` Aneesh Kumar K.V

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