From: Paul Mackerras <paulus@ozlabs.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: benh@kernel.crashing.org, mpe@ellerman.id.au,
Scott Wood <scottwood@freescale.com>,
Denis Kirjanov <kda@linux-powerpc.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH V6 20/35] powerpc/mm: Don't track subpage valid bit in pte_t
Date: Thu, 18 Feb 2016 12:11:52 +1100 [thread overview]
Message-ID: <20160218011152.GA2765@fergus.ozlabs.ibm.com> (raw)
In-Reply-To: <1448941020-15168-21-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
On Tue, Dec 01, 2015 at 09:06:45AM +0530, Aneesh Kumar K.V wrote:
> This free up 11 bits in pte_t. In the later patch we also change
> the pte_t format so that we can start supporting migration pte
> at pmd level. We now track 4k subpage valid bit as below
>
> If we have _PAGE_COMBO set, we override the _PAGE_F_GIX_SHIFT
> and _PAGE_F_SECOND. Together we have 4 bits, each of them
> used to indicate whether any of the 4 4k subpage in that group
> is valid. ie,
>
> [ group 1 bit ] [ group 2 bit ] ..... [ group 4 ]
> [ subpage 1 - 4] [ subpage 5- 8] ..... [ subpage 13 - 16]
>
> We still track each 4k subpage slot number and secondary hash
> information in the second half of pgtable_t. Removing the subpage
> tracking have some significant overhead on aim9 and ebizzy benchmark and
> to support THP with 4K subpage, we do need a pgtable_t of 4096 bytes.
I know this has already been applied, but this hunk looks wrong:
> @@ -102,7 +131,7 @@ int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
> */
> if (!(old_pte & _PAGE_COMBO)) {
> flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
> - old_pte &= ~_PAGE_HPTE_SUB;
> + old_pte &= ~_PAGE_HASHPTE | _PAGE_F_GIX | _PAGE_F_SECOND;
Shouldn't this be:
+ old_pte &= ~(_PAGE_HASHPTE | _PAGE_F_GIX | _PAGE_F_SECOND);
instead?
Paul.
next prev parent reply other threads:[~2016-02-18 1:32 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-01 3:36 [PATCH V6 00/35] powerpc/mm: Update page table format for book3s 64 Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 01/35] powerpc/mm: move pte headers to book3s directory Aneesh Kumar K.V
2015-12-14 10:46 ` [V6,01/35] " Michael Ellerman
2016-02-18 2:52 ` [PATCH V6 01/35] " Balbir Singh
2015-12-01 3:36 ` [PATCH V6 02/35] powerpc/mm: move pte headers to book3s directory (part 2) Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 03/35] powerpc/mm: make a separate copy for book3s Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 04/35] powerpc/mm: make a separate copy for book3s (part 2) Aneesh Kumar K.V
2016-02-18 2:54 ` Balbir Singh
2015-12-01 3:36 ` [PATCH V6 05/35] powerpc/mm: Move hash specific pte width and other defines to book3s Aneesh Kumar K.V
2016-02-18 4:45 ` Balbir Singh
2015-12-01 3:36 ` [PATCH V6 06/35] powerpc/mm: Delete booke bits from book3s Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 07/35] powerpc/mm: Don't have generic headers introduce functions touching pte bits Aneesh Kumar K.V
2016-02-18 4:58 ` Balbir Singh
2015-12-01 3:36 ` [PATCH V6 08/35] powerpc/mm: Drop pte-common.h from BOOK3S 64 Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 09/35] powerpc/mm: Don't use pte_val as lvalue Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 10/35] powerpc/mm: Don't use pmd_val, pud_val and pgd_val " Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 11/35] powerpc/mm: Move hash64 PTE bits from book3s/64/pgtable.h to hash.h Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 12/35] powerpc/mm: Move PTE bits from generic functions to hash64 functions Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 13/35] powerpc/booke: Move nohash headers (part 1) Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 14/35] powerpc/booke: Move nohash headers (part 2) Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 15/35] powerpc/booke: Move nohash headers (part 3) Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 16/35] powerpc/booke: Move nohash headers (part 4) Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 17/35] powerpc/booke: Move nohash headers (part 5) Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 18/35] powerpc/mm: Convert 4k hash insert to C Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 19/35] powerpc/mm: Remove the dependency on pte bit position in asm code Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 20/35] powerpc/mm: Don't track subpage valid bit in pte_t Aneesh Kumar K.V
2015-12-03 7:13 ` Anshuman Khandual
2015-12-03 18:57 ` Aneesh Kumar K.V
2016-02-18 1:11 ` Paul Mackerras [this message]
2016-02-18 1:49 ` Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 21/35] powerpc/mm: Remove pte_val usage for the second half of pgtable_t Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 22/35] powerpc/mm: Increase the width of #define Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 23/35] powerpc/mm: Convert __hash_page_64K to C Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 24/35] powerpc/mm: Convert 4k insert from asm " Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 25/35] powerpc/mm: Add helper for converting pte bit to hpte bits Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 26/35] powerpc/mm: Move WIMG update to helper Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 27/35] powerpc/mm: Move hugetlb related headers Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 28/35] powerpc/mm: Move THP headers around Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 29/35] powerpc/mm: Add a _PAGE_PTE bit Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 30/35] powerpc/mm: Don't hardcode page table size Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 31/35] powerpc/mm: Don't hardcode the hash pte slot shift Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 32/35] powerpc/nohash: Update 64K nohash config to have 32 pte fragement Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 33/35] powerpc/nohash: we don't use real_pte_t for nohash Aneesh Kumar K.V
2015-12-01 3:36 ` [PATCH V6 34/35] powerpc/mm: Use H_READ with H_READ_4 Aneesh Kumar K.V
2015-12-01 3:37 ` [PATCH V6 35/35] powerpc/mm: Don't open code pgtable_t size Aneesh Kumar K.V
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