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Date: Mon, 20 Oct 2014 09:58:10 +0800
Message-ID: <CAGZxSSSPcfEWVhwisPder1j55uibJneJAZYyMR7=2OLgpGYM6Q@mail.gmail.com>
Subject: Re: [PATCH v2] arm64: mm: use macro instead of if judgement of ZONE_DMA
From: Yifan Zhang <yifan.zhangm@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <Will.Deacon@arm.com>, Mark Rutland <Mark.Rutland@arm.com>,
        "lauraa@codeaurora.org" <lauraa@codeaurora.org>,
        "ganapatrao.kulkarni@caviumnetworks.com" 
	<ganapatrao.kulkarni@caviumnetworks.com>,
        "robh@kernel.org" <robh@kernel.org>,
        "leif.lindholm@linaro.org" <leif.lindholm@linaro.org>,
        "Yalin.Wang@sonymobile.com" <Yalin.Wang@sonymobile.com>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Yifan Zhang <zhangyf@marvell.com>
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Catalin,

No, we don't have any issues w/ current configuration. I'm just
confused why normal zone is empty in arm64 when I dumped zone info. If
it is on purpose, then I'm fine.

THX all for feedback!

BR,
Yifan

On Fri, Oct 17, 2014 at 9:28 PM, Catalin Marinas
<catalin.marinas@arm.com> wrote:
> On Fri, Oct 17, 2014 at 04:08:43AM +0100, Yifan Zhang wrote:
>> I found In current arm64 code, there is no normal zone, only DMA zone.
>>
>> Number of blocks type     Unmovable  Reclaimable      Movable
>> Reserve          CMA      Isolate
>>
>> Node 0, zone    DMA          142           12           69
>> 1           28            0
>>
>> When zone_sizes_init, zone_size[ZONE_NORMAL] is initialized to 0. (it
>> is 3.10, I didn't try the latest code base)
> [...]
>> Is this ZONE_DMA cover full memory and ZONE_NORMAL = 0 strategy on
>> purpose ? We will not use ZONE_NORMAL on arm64 ?
>
> The normal zone is still there, only that it doesn't have any pages. The
> page allocator falls back to the DMA zone, so you would not see any
> problems with normal page allocation.
>
> Are you trying to solve anything (performance?) or just what the kernel
> shows as part of the normal zone?
>
> --
> Catalin