Date: Tue, 15 Nov 2016 11:18:56 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Ganesh Mahendran <opensource.ganesh@gmail.com>
Cc: linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org,
        arve@android.com, riandrews@android.com
Subject: Re: [V2] android: binder: use VM_ALLOC to get vm area
Message-ID: <20161115101856.GB4244@kroah.com>
References: <1479203739-3806-1-git-send-email-opensource.ganesh@gmail.com>
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On Tue, Nov 15, 2016 at 05:55:39PM +0800, Ganesh Mahendran wrote:
> VM_IOREMAP is used to access hardware through a mechanism called
> I/O mapped memory. Android binder is a IPC machanism which will
> not access I/O memory.
> 
> Also VM_IOREMAP has alignment requiement which may not needed in
> binder.
>     __get_vm_area_node()
>     {
>     ...
>         if (flags & VM_IOREMAP)
>             align = 1ul << clamp_t(int, fls_long(size),
>                PAGE_SHIFT, IOREMAP_MAX_ORDER);
>     ...
>     }
> 
> This patch use VM_ALLOC to get vm area.
> 
> Below is the throughput test result:
> 
>   # ./binderThroughputTest -w 100
>   I run this command 10 times:
>                                before    after
>   average iterations per sec:  11199.9   11886.9
> 
> No performance regression found throgh binder test.
> 
> Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
> ---
>  drivers/android/binder.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

What changed from v1?

Always list that below the --- line.

thanks,

greg k-h