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 3/5] powerpc/mm: Allow more than 16 low slices
Date: Fri, 19 Jan 2018 14:00:37 +0530 [thread overview]
Message-ID: <87po66z1w2.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1c9752ac98fd3278ef448e2553053c287af42b3f.1516179904.git.christophe.leroy@c-s.fr>
Christophe Leroy <christophe.leroy@c-s.fr> writes:
> While the implementation of the "slices" address space allows
> a significant amount of high slices, it limits the number of
> low slices to 16 due to the use of a single u64 low_slices_psize
> element in struct mm_context_t
>
> On the 8xx, the minimum slice size is the size of the area
> covered by a single PMD entry, ie 4M in 4K pages mode and 64M in
> 16K pages mode. This means we could have resp. up to 1024 and 64
> slices.
>
> In order to override this limitation, this patch switches the
> handling of low_slices to BITMAPs as done already for high_slices.
Does it have a performance impact. When we switched high_slices
that was one of the question asked. Now with a topdown search we should
mostly be using the high_slices. But it will good to get numbers for
ppc64 for this change.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> v2: Usign slice_bitmap_xxx() macros instead of bitmap_xxx() functions.
>
> arch/powerpc/include/asm/book3s/64/mmu.h | 2 +-
> arch/powerpc/include/asm/mmu-8xx.h | 2 +-
> arch/powerpc/include/asm/paca.h | 2 +-
> arch/powerpc/kernel/paca.c | 3 +-
> arch/powerpc/mm/hash_utils_64.c | 13 ++--
> arch/powerpc/mm/slb_low.S | 8 ++-
> arch/powerpc/mm/slice.c | 104 +++++++++++++++++--------------
> 7 files changed, 74 insertions(+), 60 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h
> index c9448e19847a..27e7e9732ea1 100644
> --- a/arch/powerpc/include/asm/book3s/64/mmu.h
> +++ b/arch/powerpc/include/asm/book3s/64/mmu.h
> @@ -91,7 +91,7 @@ typedef struct {
> struct npu_context *npu_context;
>
> #ifdef CONFIG_PPC_MM_SLICES
> - u64 low_slices_psize; /* SLB page size encodings */
> + unsigned char low_slices_psize[8]; /* SLB page size encodings */
Can that 8 be a #define?
> unsigned char high_slices_psize[SLICE_ARRAY_SIZE];
> unsigned long slb_addr_limit;
> #else
-aneesh
next prev parent reply other threads:[~2018-01-19 8:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-17 9:22 [PATCH v2 1/5] powerpc/mm: Enhance 'slice' for supporting PPC32 Christophe Leroy
2018-01-17 9:22 ` [PATCH v2 2/5] powerpc/32: Fix hugepage allocation on 8xx at hint address Christophe Leroy
2018-01-19 8:26 ` Aneesh Kumar K.V
2018-01-19 8:49 ` Christophe LEROY
2018-01-27 9:37 ` Michael Ellerman
2018-01-17 9:22 ` [PATCH v2 3/5] powerpc/mm: Allow more than 16 low slices Christophe Leroy
2018-01-19 8:30 ` Aneesh Kumar K.V [this message]
2018-01-19 8:59 ` Christophe LEROY
2018-01-19 9:06 ` Aneesh Kumar K.V
2018-01-17 9:22 ` [PATCH v2 4/5] powerpc/8xx: Increase the number of mm slices Christophe Leroy
2018-01-17 9:22 ` [PATCH v2 5/5] powerpc/mm: Remove intermediate bitmap copy in 'slices' Christophe Leroy
2018-01-19 8:24 ` [PATCH v2 1/5] powerpc/mm: Enhance 'slice' for supporting PPC32 Aneesh Kumar K.V
2018-01-19 8:44 ` Christophe LEROY
2018-01-19 9:02 ` Aneesh Kumar K.V
2018-01-19 9:07 ` Christophe LEROY
2018-01-19 9:13 ` Aneesh Kumar K.V
2018-01-19 9:45 ` Christophe LEROY
2018-01-20 8:22 ` christophe leroy
2018-01-20 17:56 ` Segher Boessenkool
2018-01-22 7:52 ` Christophe LEROY
2018-01-23 21:47 ` Segher Boessenkool
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