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Re: ARM64 readahead: fault retry breaks mmap file read random detection

From Mark Salyzyn <salyzyn@android.com>
Newsgroups linux.kernel
Subject Re: ARM64 readahead: fault retry breaks mmap file read random detection
Date 2015-09-22 16:20 +0200
Message-ID <qbwAi-7K8-11@gated-at.bofh.it> (permalink)
References <qbgca-NQ-19@gated-at.bofh.it> <qbgvw-1pI-13@gated-at.bofh.it> <qbgYy-1Xv-9@gated-at.bofh.it> <qbja1-57d-5@gated-at.bofh.it>
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On 09/21/2015 04:51 PM, Will Deacon wrote:
> On Mon, Sep 21, 2015 at 10:36:40PM +0100, Mark Salyzyn wrote:
>> 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.
>>>
>> 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.
> You lost me; which arch-specific code are you referring to? The original
> patch (in mainline) touches a whole bunch of architectures.
>
> Will
I see I am mistaken, arm64 was the _only_ one I see that is missing ... 
<grin>

Sincerely -- Mark Salyzyn
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Thread

ARM64 readahead: fault retry breaks mmap file read random detection Mark Salyzyn <salyzyn@android.com> - 2015-09-21 22:50 +0200
  Re: ARM64 readahead: fault retry breaks mmap file read random  detection Will Deacon <will.deacon@arm.com> - 2015-09-21 23:10 +0200
    Re: ARM64 readahead: fault retry breaks mmap file read random  detection Mark Salyzyn <salyzyn@android.com> - 2015-09-21 23:40 +0200
      Re: ARM64 readahead: fault retry breaks mmap file read random  detection Will Deacon <will.deacon@arm.com> - 2015-09-22 02:00 +0200
        Re: ARM64 readahead: fault retry breaks mmap file read random  detection Mark Salyzyn <salyzyn@android.com> - 2015-09-22 16:20 +0200

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