From: David Daney <ddaney.cavm@gmail.com>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Huacai Chen <chenhc@lemote.com>, John Crispin <john@phrozen.org>,
"Steven J. Hill" <Steven.Hill@imgtec.com>,
Aurelien Jarno <aurelien@aurel32.net>,
linux-mips@linux-mips.org, Fuxin Zhang <zhangfx@lemote.com>,
Zhangjin Wu <wuzhangjin@gmail.com>
Subject: Re: [PATCH V2 4/8] MIPS: Add NUMA support for Loongson-3
Date: Wed, 04 Jun 2014 10:22:17 -0700 [thread overview]
Message-ID: <538F55C9.7090905@gmail.com> (raw)
In-Reply-To: <20140604064601.GU5157@linux-mips.org>
On 06/03/2014 11:46 PM, Ralf Baechle wrote:
>
> A more important value which I haven't noticed the Looongson patches to
> modify is SECTION_SIZE_BITS in <asm/sparsemem.h>:
>
> #if defined(CONFIG_MIPS_HUGE_TLB_SUPPORT) && defined(CONFIG_PAGE_SIZE_64KB)
> # define SECTION_SIZE_BITS 29
> #else
> # define SECTION_SIZE_BITS 28
> #endif
>
> Don't ask me why its definition depends on MIPS_HUGE_TLB_SUPPORT and
> PAGE_SIZE_64KB - the value describes the larges chunk of contiguous
> memory (that is for example memory per node) and that doesn't depend
> on these CONFIG_* symbols.
>
I think I can answer that. We do the same thing for OCTEON I think.
IIRC, with SPARSEMEM, you cannot allocate high order pages that span
multiple sections. Therefore you have to have the sections be at least
as large as a huge page. in the case of CONFIG_PAGE_SIZE_64KB, the huge
pages are 512MB which doesn't fit in 28 bits.
David.
> Ralf
>
>
next prev parent reply other threads:[~2014-06-04 17:22 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-13 0:24 [PATCH V2 0/8] MIPS: Loongson-3: Add NUMA and Loongson-3B support Huacai Chen
2014-04-13 0:24 ` [PATCH V2 1/8] MIPS: Support hard limit of cpu count (nr_cpu_ids) Huacai Chen
2014-04-14 14:48 ` Andreas Herrmann
2014-04-13 0:24 ` [PATCH V2 2/8] MIPS: Support CPU topology files in sysfs Huacai Chen
2014-04-14 15:04 ` Andreas Herrmann
2014-04-13 0:24 ` [PATCH V2 3/8] MIPS: Loongson: Modify ChipConfig register definition Huacai Chen
2014-04-13 0:24 ` [PATCH V2 4/8] MIPS: Add NUMA support for Loongson-3 Huacai Chen
2014-06-03 22:47 ` Ralf Baechle
2014-06-03 23:47 ` David Daney
2014-06-04 6:46 ` Ralf Baechle
2014-06-04 17:22 ` David Daney [this message]
2014-06-05 9:15 ` Huacai Chen
2014-04-13 0:24 ` [PATCH V2 5/8] MIPS: Add numa api support Huacai Chen
2014-04-13 0:24 ` [PATCH V2 6/8] MIPS: Add Loongson-3B support Huacai Chen
2014-04-13 0:24 ` [PATCH V2 7/8] MIPS: Loongson-3: Enable the COP2 usage Huacai Chen
2014-04-13 0:24 ` [PATCH V2 8/8] MIPS: Loongson: Rename CONFIG_LEMOTE_MACH3A to CONFIG_LOONGSON_MACH3X Huacai Chen
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