From mboxrd@z Thu Jan  1 00:00:00 1970
From: salyzyn@android.com (Mark Salyzyn)
Date: Mon, 21 Sep 2015 14:36:40 -0700
Subject: ARM64 readahead: fault retry breaks mmap file read random
 detection
In-Reply-To: <20150921210938.GC7356@arm.com>
References: <1442868028-27055-1-git-send-email-salyzyn@android.com>
 <20150921210938.GC7356@arm.com>
Message-ID: <56007868.8050605@android.com>
To: linux-arm-kernel@lists.infradead.org
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On 09/21/2015 02:09 PM, Will Deacon wrote:
> On Mon, Sep 21, 2015 at 09:39:50PM +0100, Mark Salyzyn wrote:
>> Description from commit 45cac65b0fcd
>>      ("readahead: fault retry breaks mmap file read random detection")
>> . . .
>> Yup, arm64 needs this too! Random read improves by 250%, sequential
>> read improves by 40%, and random write by 400% to an eMMC device with
>> dm crypto wrapped around it.
> Thanks for this. This must've gone in whilst we were developing the initial
> version of the arm64 port and has since gone unnoticed.
>
> I'll queue it on the arm64 fixes branch and send a pull request after
> some testing.
>
> Will

As noted, this fix may need to be propagated to all the arch-specific 
code, I was not in a position to check this out on arm (32 bit) and the 
benchmarking code I used did not immediately port to 32-bit.

Sincerely -- Mark Salyzyn

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Subject: Re: ARM64 readahead: fault retry breaks mmap file read random
 detection
To: Will Deacon <will.deacon@arm.com>
References: <1442868028-27055-1-git-send-email-salyzyn@android.com>
 <20150921210938.GC7356@arm.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Riley Andrews <riandrews@android.com>, Shaohua Li <shli@kernel.org>,
        Shaohua Li <shaohua.li@fusionio.com>, Rik van Riel <riel@redhat.com>,
        Wu Fengguang <fengguang.wu@intel.com>,
        Catalin Marinas <Catalin.Marinas@arm.com>,
        Vladimir Murzin <Vladimir.Murzin@arm.com>,
        Dave P Martin <Dave.Martin@arm.com>,
        David Hildenbrand <dahi@linux.vnet.ibm.com>,
        James Morse <James.Morse@arm.com>, Mark Rutland <Mark.Rutland@arm.com>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
From: Mark Salyzyn <salyzyn@android.com>
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Date: Mon, 21 Sep 2015 14:36:40 -0700
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On 09/21/2015 02:09 PM, Will Deacon wrote:
> On Mon, Sep 21, 2015 at 09:39:50PM +0100, Mark Salyzyn wrote:
>> Description from commit 45cac65b0fcd
>>      ("readahead: fault retry breaks mmap file read random detection")
>> . . .
>> Yup, arm64 needs this too! Random read improves by 250%, sequential
>> read improves by 40%, and random write by 400% to an eMMC device with
>> dm crypto wrapped around it.
> Thanks for this. This must've gone in whilst we were developing the initial
> version of the arm64 port and has since gone unnoticed.
>
> I'll queue it on the arm64 fixes branch and send a pull request after
> some testing.
>
> Will

As noted, this fix may need to be propagated to all the arch-specific 
code, I was not in a position to check this out on arm (32 bit) and the 
benchmarking code I used did not immediately port to 32-bit.

Sincerely -- Mark Salyzyn