From: David Gibson <dwg@au1.ibm.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: paulus@samba.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org
Subject: Re: [PATCH -V7 09/18] powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format
Date: Tue, 30 Apr 2013 15:17:18 +1000 [thread overview]
Message-ID: <20130430051718.GB20202@truffula.fritz.box> (raw)
In-Reply-To: <1367177859-7893-10-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
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On Mon, Apr 29, 2013 at 01:07:30AM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>
> We will be switching PMD_SHIFT to 24 bits to facilitate THP impmenetation.
> With PMD_SHIFT set to 24, we now have 16MB huge pages allocated at PGD level.
> That means with 32 bit process we cannot allocate normal pages at
> all, because we cover the entire address space with one pgd entry. Fix this
> by switching to a new page table format for hugepages. With the new page table
> format for 16GB and 16MB hugepages we won't allocate hugepage directory. Instead
> we encode the PTE information directly at the directory level. This forces 16MB
> hugepage at PMD level. This will also make the page take walk much simpler later
> when we add the THP support.
>
> With the new table format we have 4 cases for pgds and pmds:
> (1) invalid (all zeroes)
> (2) pointer to next table, as normal; bottom 6 bits == 0
> (3) leaf pte for huge page, bottom two bits != 00
> (4) hugepd pointer, bottom two bits == 00, next 4 bits indicate size
> of table
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Mostly ok, except that in several pages your comments imply you have
16M and 16M page directory levels, but you haven't actually made that
change yet.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2013-04-30 5:19 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-28 19:37 [PATCH -V7 00/18] THP support for PPC64 (Patchset 1) Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 01/18] mm/THP: HPAGE_SHIFT is not a #define on some arch Aneesh Kumar K.V
2013-04-30 2:21 ` David Gibson
2013-04-30 2:24 ` David Gibson
2013-04-30 3:42 ` Aneesh Kumar K.V
2013-04-30 5:01 ` David Gibson
2013-05-03 18:51 ` Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 02/18] mm/THP: Add pmd args to pgtable deposit and withdraw APIs Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 03/18] mm/THP: withdraw the pgtable after pmdp related operations Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 04/18] powerpc: Use signed formatting when printing error Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 05/18] powerpc: Save DAR and DSISR in pt_regs on MCE Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 06/18] powerpc: Don't hard code the size of pte page Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 07/18] powerpc: Don't truncate pgd_index wrongly Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 08/18] powerpc: New hugepage directory format Aneesh Kumar K.V
2013-04-30 5:16 ` David Gibson
2013-04-28 19:37 ` [PATCH -V7 09/18] powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format Aneesh Kumar K.V
2013-04-30 5:17 ` David Gibson [this message]
2013-06-06 22:42 ` Scott Wood
2013-06-07 3:55 ` Aneesh Kumar K.V
2013-06-07 19:17 ` Scott Wood
2013-06-08 16:57 ` Aneesh Kumar K.V
2013-06-11 20:53 ` Scott Wood
2013-06-11 22:50 ` Scott Wood
2013-06-12 6:30 ` Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 10/18] powerpc: Reduce the PTE_INDEX_SIZE Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 11/18] powerpc: Move the pte free routines from common header Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 12/18] powerpc: Reduce PTE table memory wastage Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 13/18] powerpc: Use encode avpn where we need only avpn values Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 14/18] powerpc: Decode the pte-lp-encoding bits correctly Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 15/18] powerpc: Fix hpte_decode to use the correct decoding for page sizes Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 16/18] powerpc: print both base and actual page size on hash failure Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 17/18] powerpc: Print page size info during boot Aneesh Kumar K.V
2013-04-28 19:37 ` [PATCH -V7 18/18] powerpc: Update tlbie/tlbiel as per ISA doc Aneesh Kumar K.V
2013-04-30 6:15 ` David Gibson
2013-04-30 17:21 ` Aneesh Kumar K.V
2013-05-01 5:26 ` David Gibson
2013-05-01 7:47 ` Aneesh Kumar K.V
2013-05-01 7:52 ` Simon Jeons
2013-05-01 11:36 ` David Gibson
2013-05-02 5:23 ` David Gibson
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