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From: "Aneesh Kumar K.V" <aneesh.kumar@linux•vnet.ibm.com>
To: christophe leroy <christophe.leroy@c-s•fr>,
	Benjamin Herrenschmidt <benh@kernel•crashing.org>,
	Paul Mackerras <paulus@samba•org>,
	Michael Ellerman <mpe@ellerman•id.au>,
	Scott Wood <oss@buserror•net>
Cc: linux-kernel@vger•kernel.org, linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH v2 2/3] powerpc: get hugetlbpage handling more generic
Date: Tue, 20 Sep 2016 08:15:09 +0530	[thread overview]
Message-ID: <874m5bxpai.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <2c8682d7-78ce-0aaf-79bd-85a85849e227@c-s.fr>

christophe leroy <christophe.leroy@c-s•fr> writes:

>>
>>
>>>  	for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
>>>  		unsigned shift;
>>>  		unsigned pdshift;
>>> @@ -860,16 +807,31 @@ static int __init hugetlbpage_init(void)
>>>  		 * if we have pdshift and shift value same, we don't
>>>  		 * use pgt cache for hugepd.
>>>  		 */
>>> -		if (pdshift != shift) {
>>> +		if (pdshift > shift) {
>>>  			pgtable_cache_add(pdshift - shift, NULL);
>>>  			if (!PGT_CACHE(pdshift - shift))
>>>  				panic("hugetlbpage_init(): could not create "
>>>  				      "pgtable cache for %d bit pagesize\n", shift);
>>> +		} else if (!hugepte_cache) {
>>> +			/*
>>> +			 * Create a kmem cache for hugeptes.  The bottom bits in
>>> +			 * the pte have size information encoded in them, so
>>> +			 * align them to allow this
>>> +			 */
>>> +			hugepte_cache = kmem_cache_create("hugepte-cache",
>>> +							  sizeof(pte_t),
>>> +							  HUGEPD_SHIFT_MASK + 1,
>>> +							  0, NULL);
>>> +			if (hugepte_cache == NULL)
>>> +				panic("%s: Unable to create kmem cache "
>>> +				      "for hugeptes\n", __func__);
>>> +
>>
>>
>> We don't need hugepte_cache for book3s 64K. I guess we will endup
>> creating one here ?
>
> Should not, because on book3s 64k, we will have pdshift > shift
> won't we ?
>

on 64k book3s, we have pdshift == shift and we don't need to create 
hugepd cache on book3s 64k.

-aneesh

  reply	other threads:[~2016-09-20  2:45 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-16  7:40 [PATCH v2 0/3] powerpc: implementation of huge pages for 8xx Christophe Leroy
2016-09-16  7:40 ` [PATCH v2 1/3] powerpc: port 64 bits pgtable_cache to 32 bits Christophe Leroy
2016-09-19  5:22   ` Aneesh Kumar K.V
2016-09-19 18:46     ` christophe leroy
2016-09-16  7:40 ` [PATCH v2 2/3] powerpc: get hugetlbpage handling more generic Christophe Leroy
2016-09-19  5:45   ` Aneesh Kumar K.V
2016-09-19 18:32     ` christophe leroy
2016-09-20  2:45       ` Aneesh Kumar K.V [this message]
2016-09-21  6:13     ` Christophe Leroy
2016-09-19  5:50   ` Aneesh Kumar K.V
2016-09-19 18:36     ` christophe leroy
2016-09-20  2:28       ` Aneesh Kumar K.V
2016-09-20  5:22         ` Christophe Leroy
2016-09-16  7:40 ` [PATCH v2 3/3] powerpc/8xx: Implement support of hugepages Christophe Leroy

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