From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org, David Gibson <dwg@au1.ibm.com>
Subject: Re: [PATCH -V6 05/27] powerpc: New hugepage directory format
Date: Tue, 23 Apr 2013 14:12:04 +0530 [thread overview]
Message-ID: <87k3ntprj7.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130423070103.GB30092@iris.ozlabs.ibm.com>
Paul Mackerras <paulus@samba.org> writes:
> On Mon, Apr 22, 2013 at 03:30:39PM +0530, Aneesh Kumar K.V wrote:
>
>> Instead of storing shift value in hugepd pointer we use mmu_psize_def index
>> so that we can fit all the supported hugepage size in 4 bits
>
> That works, but does mean that we have to scan the mmu_psize_defs[]
> array to work out the encoding for a particular page size.
We do the scan only when allocating hugepgd. While walking it is only
mmu_psize_defs dereference. Yes, that could possibly have a performance
impact, but having a well defined way to map page shift to a smaller
index and using the same method all the place is nice. I will try to
measure the impact and switch to the below method if needed.
> Instead,
> we could use the fact that all large page sizes are powers of 4, as
> are all supported page sizes on embedded processors. So we could
> encode using page_code = (page_order - 12) / 2, where page_order is
> the log base 2 of the page size, and that lets us represent all power
> of 4 page sizes between 2^12 (4kB) and 2^42 bytes (4TB).
I guess i can add this as an addon patch on the top of the series if the
current patch series is going in to Benh's tree ?
-aneesh
next prev parent reply other threads:[~2013-04-23 8:54 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-22 10:00 [PATCH -V6 00/27] THP support for PPC64 Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 01/27] powerpc: Use signed formatting when printing error Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 02/27] powerpc: Save DAR and DSISR in pt_regs on MCE Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 03/27] powerpc: Don't hard code the size of pte page Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 04/27] powerpc: Don't truncate pgd_index wrongly Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 05/27] powerpc: New hugepage directory format Aneesh Kumar K.V
2013-04-23 7:01 ` Paul Mackerras
2013-04-23 8:42 ` Aneesh Kumar K.V [this message]
2013-04-24 5:47 ` Paul Mackerras
2013-04-25 6:00 ` Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 06/27] powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 07/27] powerpc: Reduce the PTE_INDEX_SIZE Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 08/27] powerpc: Move the pte free routines from common header Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 09/27] powerpc: Reduce PTE table memory wastage Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 10/27] powerpc: Use encode avpn where we need only avpn values Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 11/27] powerpc: Decode the pte-lp-encoding bits correctly Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 12/27] powerpc: Fix hpte_decode to use the correct decoding for page sizes Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 13/27] powerpc: print both base and actual page size on hash failure Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 14/27] powerpc: Print page size info during boot Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 15/27] powerpc: Update tlbie/tlbiel as per ISA doc Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 16/27] mm/THP: HPAGE_SHIFT is not a #define on some arch Aneesh Kumar K.V
2013-04-22 15:43 ` Andrea Arcangeli
2013-04-22 10:00 ` [PATCH -V6 17/27] mm/THP: Add pmd args to pgtable deposit and withdraw APIs Aneesh Kumar K.V
2013-04-22 15:46 ` Andrea Arcangeli
2013-04-22 10:00 ` [PATCH -V6 18/27] mm/THP: withdraw the pgtable after pmdp related operations Aneesh Kumar K.V
2013-04-22 15:49 ` Andrea Arcangeli
2013-04-24 9:08 ` Aneesh Kumar K.V
2013-04-24 15:14 ` Andrea Arcangeli
2013-04-25 6:11 ` Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 19/27] powerpc/THP: Double the PMD table size for THP Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 20/27] powerpc/THP: Implement transparent hugepages for ppc64 Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 21/27] powerpc: move find_linux_pte_or_hugepte and gup_hugepte to common code Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 22/27] powerpc: Update find_linux_pte_or_hugepte to handle transparent hugepages Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 23/27] powerpc: Replace find_linux_pte with find_linux_pte_or_hugepte Aneesh Kumar K.V
2013-04-24 6:29 ` Paul Mackerras
2013-04-22 10:00 ` [PATCH -V6 24/27] powerpc: Update gup_pmd_range to handle transparent hugepages Aneesh Kumar K.V
2013-04-22 10:00 ` [PATCH -V6 25/27] powerpc/THP: Add code to handle HPTE faults for large pages Aneesh Kumar K.V
2013-04-22 10:01 ` [PATCH -V6 26/27] powerpc/THP: Enable THP on PPC64 Aneesh Kumar K.V
2013-04-22 10:01 ` [PATCH -V6 27/27] powerpc: Optimize hugepage invalidate Aneesh Kumar K.V
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